miwadi is an irish soft drink brand owned by britvic , and formerly by cantrell and cochrane ( c&c ) , bottled in dublin , cork and belfast .

its name comes from the initial letters of c&c 's predecessor company , mineral water distributors , which was formed in 1927 .

the range includes blackcurrant , lemon , lime , and orange & pineapple fruit squashes , with additional flavours produced on a seasonal basis , such as peppermint , and clove .

the slogan of miwadi is " it 's not your wadi , it 's miwadi " , seen on miwadi bottles and commercials .

the drink suffered declining sales during the 1990s , occupying only 16.4 % of the market share by 1995 , but as of 2005 it accounted for 37 % of fruit squash sold in the irish market .

miwadi

miwadi ireland - check out our new miwadi mini orange . . . | facebook
miwadi ireland - miwadi mini makes water fun anywhere ! and . . . | facebook
miwadi is introducing a new range of miwadi minis , packs of super concentrated dilute drops that can be added to flavour water .
rtd - ready to drink - dilute 1 part miwadi with 9 parts water .
miwadi takes its name from mineral water distributors , the company which was originally formed in 1927 in nassau place in dublin , which produced miwadi , c & c ; and club products .
a little splash of miwadi can help you drink the water you need each day . your miwadi orange contains added vitamins and zinc that contribute to a healthy immune system and the growth of healthy bones .
ireland’s leading dilute brand , miwadi , has announced the introduction of the latest addition to their range , miwadi 0 % sugar . it is the first dilute in the irish market with 0 % sugar .
miwadi is the no . 1 soft drinks brand in the republic of ireland ( neilsen scantrack 8th october 2017 )
miwadi’s 0 % sugar will be available in three flavours ; orange , apple & pear and apple & berry .
made with real fruit , our miwadi 0 % sugar is bursting with great taste and the benefits of added vitamins .
where’s our miwadi mini fan naomi ' s favourite subject ? guess below and be in to win a €50 smyths toy voucher .
the packs are aimed at families “out and about” on excursions or outings . dee cunniam , marketing manager for miwadi mini , explains : “miwadi mini is the ultimate handbag hero and pocket refreshment . we have carried out extensive research with consumers in ireland and pocket size drops is the format of the future for dilutes so we are thrilled miwadi is taking the lead . the fact that it contains just 5 calories per squeeze and 0 % sugar , miwadi mini should become the go - to for on the go refreshment , making water fun anywhere . ”
miwadi is an iconic irish brand made with real fruit juice and offers a simple way to make drinking water tasty and fun for families .
my goodness - mi wadi . blackcurrant flavored concentrate packed with natures goodness . it ' s not your wadi , it ' s miwadi .
shake well – makes 20 tasty drinks – mix just one squeeze per serving of water for all the thirst quenching tastiness of miwadi at its best .
shake well . 3 . 3ml concentrate per 250ml of water . mix just one squeeze per serving of water for all the thirst quenching tastiness of miwadi at its best
shake well . 3 . 3ml concentrate per 250ml of water . mix just one squeeze per serving of water for all the thirst quenching tastiness of miwadi at its best
shake well . 3 . 3ml concentrate per 250ml of water . mix just one squeeze per serving of water for all the thirst quenching tastiness of miwadi at its best
the new range’s launch will be supported by a national multimedia campaign including digital and outdoor advertising , a new miwadi tv advertisement and heavy weight in - store promotional and sampling campaigns .
contained in handbag sized squeezable packs , the miwadi mini range contains real fruit juice and 0 % sugar . the packs are available in three flavours : apple & strawberry , peach & mango and tropical fruits .
miwadi is set to make a big splash this summer , with our breath - taking new tv campaign ! our 30 second ad follows the adventures of a group of irish kids as they bring a public park to life with their imaginations , and take us all along on their journey .
production increased throughout the 1950 ' s and 1960’s following the introduction of machines . screw caps replaced corks and new flavours such as blackcurrant were added to the range . miwadi was mainly sold in chemists as a glucose drink but quickly became more popular in larger grocers and supermarkets making it accessible to more consumers .
speaking about the latest range , leonie doyle , marketing director of britvic ireland commented , “we are proud to introduce the first 0 % sugar dilute to the irish market to add to the rest of our range of healthy options . over 320 million refreshing glasses of miwadi are consumed every year in ireland , making it ireland’s number one dilute . ”
by the 1990s it was the second biggest branded cordial in northern ireland , and its ‘my goodness , miwadi’ tv campaign was extremely successful , catapulting the brand to become ireland’s no . 1 cordial which it remains today source : neilsen scantrack data to 8 october 2017 ) . it was acquired by britvic in 2007 forming britvic ireland and is today known as an industry leader and a leader in no / low sugar in the republic of ireland .
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each pack makes 20 drinks . the rrp is €2 . 89 from all retailers and convenience shops nationwide .
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of an adult ' s guideline daily amount based on a 2000 kcal diet * dilute as per manufacturer’s instructions . it’s important to add extra water if given to toddlers
fruit juices from concentrate 10 % ( apple ( 4 . 6 % ) , strawberry ( 3 % ) , blackcurrant ( 1 . 4 % ) , cherry ( 1 % ) )
of an adult ' s guideline daily amount based on a 2000 kcal diet * dilute as per manufacturer’s instructions . it is important to add extra water if given to toddlers .
* of an adult ' s guideline daily amount based on a 2000 kcal diet * dilute as per manufacturer’s instructions . it’s important to add extra water if given to toddlers .
rtd - ready to drink - shake well . 3 . 3ml of concentrate per 250ml of water .
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it was originally manufactured by hand ( date is referenced above ) . the bottles were washed and then passed along a line where they were filled , labelled , packed into wooden crates and distributed around dublin by horse and cart . by the 1930’s the production capacity was 60 dozen per day and the most popular flavour was grapefruit .
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vitamin b6 contributes to the normal function of the immune system . zinc contributes to the maintenance of normal bones .
while every care has been taken to ensure product information is correct , food products are constantly being reformulated , so ingredients , nutrition content , dietary and allergens may change . you should always read the product label and not rely solely on the information provided on the website .
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1 . the promoter : the promoter is britvic ireland limited , registered office at 25 / 28 north wall quay , dublin 1 , having its place o . . .
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all orders of $ 100 or more of eligible items across any product category qualify for free standard shipping .
your order will be delivered 5 - 8 business days after all your items are available to ship .
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if you place an order wednesday - sunday for a perishable item , we will ship it the next available business day .
the new product also contains only natural colours and flavours and real fruit juice . it also contains stevia extracts , meaning that each glass contains five calories or less .
ireland ' s wholesale price index fell by 3 . 3 % in may compared to 2017
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warning : do not refill . do not drink undiluted . if diluting for toddlers add extra water . not recommended for use or to be handled by children under 36 months . avoid contact with eyes ; in case of contact promptly rinse with water .
want to get in touch ? call our consumer care team in roi on 1800 696 127 , gb & ni on 0800 032 1767 or visit urltoken and email us . britvic ireland ltd . , p . o . box 2020 , dublin 10 , ireland . britvic soft drinks ltd . , hemel hempstead , hp2 4tz , uk .
britvic ireland ltd . , p . o . box 2020 , dublin 10 , ireland . britvic soft drinks ltd . , hemel hempstead , hp2 4tz , uk .
warning : do not refill . do not drink undiluted . if diluting for toddlers and extra water . not recommended for use or to be handled by children under 36 months . avoid contact with eyes ; in case of contact promptly rinse with water .
highly concentrated sugar free orange soft drink with sweetener – no added sugar concentrated .
warning : do not refill . do not drink undiluted . if diluting for toddlers add extra water


the palmer drought index , sometimes called the palmer drought severity index and often abbreviated pdsi , is a measurement of dryness based on recent precipitation and temperature .

it was developed by meteorologist wayne palmer , who first published his method in the 1965 paper meteorological drought for the office of climatology of the u.s. weather bureau .

the palmer drought index is based on a supply-and-demand model of soil moisture .

supply is comparatively straightforward to calculate , but demand is more complicated as it depends on many factors , not just temperature and the amount of moisture in the soil but also hard-to-calibrate factors including evapotranspiration and recharge rates .

palmer tried to overcome these difficulties by developing an algorithm that approximated them based on the most readily available data , precipitation and temperature .

the index has proven most effective in determining long-term drought , a matter of several months , but it is not as good with conditions over a matter of weeks .

it uses a 0 as normal , and drought is shown in terms of negative numbers ; for example , negative 2 is moderate drought , negative 3 is severe drought , and negative 4 is extreme drought .

palmer 's algorithm also is used to describe wet spells , using corresponding positive numbers .

palmer also developed a formula for standardizing drought calculations for each individual location based on the variability of precipitation and temperature at that location .

the palmer index can therefore be applied to any site for which sufficient precipitation and temperature data is available .

critics have complained that the utility of the palmer index is weakened by the arbitrary nature of palmer 's algorithms , including the technique used for standardization .

the palmer index 's inability to account for snow and frozen ground also is cited as a weakness .

the palmer index is widely used operationally , with palmer maps published weekly by the united states government 's national oceanic and atmospheric administration .

it also has been used by climatologists to standardize global long-term drought analysis .

global palmer data sets have been developed based on instrumental records beginning in the 19th century .

in addition , dendrochronology has been used to generate estimated palmer index values for north america for the past 2000 years , allowing analysis of long term drought trends .

it has also been used as a means of explaining the late bronze age collapse .

in the us , regional palmer maps are featured on the cable channel weatherscan .

palmer drought index

percent area of contiguous u . s . in palmer drought index moderate to extreme
monthly maps of drought conditions in the contiguous u . s . as measured by the palmer drought severity index , palmer hydrological drought index , palmer modified drought index , and palmer z - index ( palmer , 1965 ) are provided for january 1900—june 2018 . animations of any set of monthly maps for any period desired can be viewed by selecting the beginning and ending dates of interest .
wells , nathan , steve goddard , michael j . hayes , 2004 : a self - calibrating palmer drought severity index . j . climate , 17 , 2335–2351
the palmer drought severity index ( pdsi ) and crop moisture index ( cmi ) are indices of the relative dryness or wetness affecting water sensitive economies . the data is provided in graphical and tabular formats , for the contiguous united states .
to quantify drought and monitor its development , many drought indices have been developed and applied . among them , the palmer drought severity index ( pdsi ) is the most prominent index of meteorological drought used in the united states for drought monitoring and research , and its variants have been used to quantify long - term changes in aridity over land in the 20
alley , w . m . , 1984 : the palmer drought severity index : limitations and assumptions . j . climate appl . meteor . 23 , 1000 - 1009
dai , a . , 2011a : characteristics and trends in various forms of the palmer drought severity index ( pdsi ) during 1900 - 2008 . j . geophys . res . , 116 , d12115
dai , aiguo & national center for atmospheric research staff ( eds ) . last modified 12 jul 2017 .
the climate data guide : palmer drought severity index ( pdsi ) .
retrieved from urltoken
palmer , w . c . , 1968 : keeping track of crop moisture conditions , nationwide : the new crop moisture index . weatherwise , 21 , 156 - 161 .
dai , a . , k . e . trenberth , and t . qian , 2004 : a global data set of palmer drought severity index for 1870 - 2002 : relationship with soil moisture and effects of surface warming . j . hydrometeorology , 5 , 1117 - 1130
palmer , w . c , 1965 : meteorological drought . res . paper no . 45 , 58pp . , dept . of commerce , washington , d . c .
the palmer drought severity index ( pdsi ) uses readily available temperature and precipitation data to estimate relative dryness . it is a standardized index that spans - 10 ( dry ) to + 10 ( wet ) . it has been reasonably successful at quantifying long - term drought . as it uses temperature data and a physical water balance model , it can capture the basic effect of global warming on drought through changes in potential evapotranspiration . monthly pdsi values do not capture droughts on time scales less than about 12 months ; more pros and cons are discussed in the expert guidance .
national drought mitigation center the national drought mitigation center works closely with nidis to provide drought - related resources and information . for more news and impacts information , visit the ndmc .
usda federal drought assistance for information on resources available to help aid in the recovery from this year’s drought , visit the usda .
home > monitoring and data > u . s . climate data > drought monitoring
keyantash , john , john a . dracup , 2002 : the quantification of drought : an evaluation of drought indices . bull . amer . meteor . soc . , 83 , 1167–1180 .
recently , the pdsi was criticized for its inability to depict droughts on time scales shorter than 12 months when monthly pdsi values were used . this is not unexpected as the pdsi was designed to be strongly auto - correlated in order to account for the impact of land memory on drought conditions . however , the palmer model also computes the un - smoothed z - index which can be used to track short - term agricultural drought , since it responds quickly to changes in soil moisture . for quantifying long - term changes in aridity and droughts , the relatively long intrinsic time scale of monthly pdsi should not be a problem .
from this perspective , the pdsi and sc _ pdsi may be considered superior to other statistically based drought indices . this is because the pdsi and sc _ pdsi can account for the basic effect of global warming through palmer ' s water balance model on droughts and wet spells . the effect of global warming may have already occurred during the 20
comprises seven federal agencies which work collaboratively to support state , tribal , local , and private sector approaches to managing drought risks and impacts .
dai , a . , 2011b : drought under global warming : a review . wiley interdisciplinary reviews : climate change , 2 , 45 - 65
the national drought mitigation center website was recently updated , so it ' s possible the url of the page you were looking for has changed .
richard r . heim jr . , 2002 : a review of twentieth - century drought indices used in the united states . bull . amer . meteor . soc . , 83 , 1149–1165
zhao , t . , and a . dai ( 2015 ) : the magnitude and causes of global drought changes in the 21st century under a low - moderate emissions scenario . j . climate , , 28 , 4490–4512
[ 1965 ] with the intent to measure the cumulative departure in surface water balance . it incorporates antecedent and current moisture supply ( precipitation , p ) and demand ( potential evapotranspiration , pe ) into a hydrological accounting system , which includes a 2 - layer bucket - type model for soil moisture calculations . the pdsi is a standardized measure , ranging from about - 10 ( dry ) to + 10 ( wet ) with values below - 3 representing severe to extreme drought . the standardization used by palmer was based on limited data from the central u . s . and tends to yield more severe pdsi in the great plains than other u . s . regions . to improve the spatial comparability ,
the pdsi is also imprecise in its treatment of all precipitation as immediately available rainfall ( i . e . , no delayed runoff from melting snow ) , its lack of impact of vegetation or frozen soils on evaporation , and some other processes . despite all these caveats , dai et al . [ 2004 ] and dai [ 2011a ] showed that the pdsi values are significantly correlated with measured soil moisture content in the warm season and streamflow over many regions over the world , and satellite observed land water storage changes , and these correlations are comparable over the u . s . and many other parts of the world . this suggests that the pdsi can be used as a measure of drought over land , especially over the low and middle latitudes . this is largely due to the fact that the normalization in the palmer model minimizes the errors associated with many of the assumptions made by palmer [ 1965 ] and that actual evaporation is often determined , to a large degree , by the availability of soil moisture ( and thus affected by precipitation ) , not only by pe , over many land areas . also , using annual values should minimize the seasonal effect of snowfall on the surface water balance .
burke , e . j . , and s . j . brown ( 2008 ) , evaluating uncertainties in the projection of future drought , j . hydrometeorol . , 9 , 292–299 , doi : 10 . 1175 / 2007jhm929 . 1
west : outside the withdrawal of d0 from a small area in northeast montana , where most locations recorded between one and two inches of rain , the drought monitor depiction is unchanged from the previous week . significant rains from the southwest monsoon have yet to reach most of arizona , and only scattered locations across southern and eastern new mexico recorded over an inch of rain this past week . but a late start to the monsoon is hardly unusual , and conditions do not warrant drought degradation yet .
midwest : a few inches of rain wiped out the abnormally dry area in central iowa , and a re - assessment of earlier rains led to the removal of d0 conditions from central indiana as well . in contrast , a relatively dry week kept abnormally dry conditions unchanged in east - central michigan , scattered areas across northern and western minnesota , and northeastern illinois . areas of drought cover southern iowa and both the northern and southwestern parts of missouri . abnormally dry conditions ( d0 ) covered much of the rest of the show - me state , but moderate to heavy rains eliminated a large area of d0 in southeastern missouri . despite areas of significant rainfall in some other parts of missouri , no marked changes in dryness or drought were noted , though a small area in north - central missouri slipped into d2 ( extreme drought ) conditions .
trenberth , k . e . , a . dai , g . van der schrier , p . d . jones , j . barichivich , k . r . briffa , and j . sheffield ^ , 2014 : global warming and changes in drought . nature climate change , 4 , 17 - 22
northeast : most areas of dryness and drought recorded at least light precipitation , with a few swaths receiving 1 to locally 2 inches ; however , these amounts were insufficient to improve conditions significantly , especially with the heat wave that enveloped the region late in the period . the only change introduced was a small expansion of abnormal dryness into a few additional counties in upstate new york .
on the positive side , the pdsi is based on a physical water - balance model , uses both precipitation and surface air temperature ( and other variables when pe _ pm is used ) as input , and takes the precedent condition into account , in contrast to most other drought indices that are based purely on past statistics of certain climate variable ( s ) , which often includes precipitation alone .
high plains : in colorado and wyoming , most areas remained unchanged ; most of wyoming remained out of dryness , and conditions worsen progressively moving south , with extreme to exceptional drought covering southern colorado . deficient precipitation and enhanced evaporative loss over the past few months led to limited expansion of d0 and d1 in areas near the central part of the border . farther east , dryness led to some deterioration in kansas . d3 pushed into part of south - central kansas while extreme drought expanded into a larger part of northeastern kansas . in the dakotas , very heavy rains and flooding late in the period covered a swath across east - central south dakota , leading to a band of 1 - to 2 - category improvement , with southern reaches of the old d2 area climbing to d0 . this area will have to be assessed next week to get a better sense of how this intense rainfall episode changed the drought situation there . moderate to heavy rains ( but only isolated minor flooding ) pelted western north dakota as well , prompting the removal of abnormal dryness over much of the western part of the state . small - scale improvements were made in a few other dry areas where rain was heaviest .
the discussion in the looking ahead section is simply a description of what the official national guidance from the national weather service ( nws ) national centers for environmental prediction is depicting for current areas of dryness and drought . the nws forecast products utilizedinclude the hpc 5 - day qpf and 5 - day mean temperature progs , the 6 - 10 day outlooks of temperature and precipitation probability , and the 8 - 14day outlooks of temperature and precipitation probability , valid as of late wednesday afternoon of the usdm release week . the nws forecast webpage used for this section is : urltoken
south : heavy rain – 3 . 5 to locally over 8 . 0 inches – dowsed much of the dry area in tennessee , eliminating most of the abnormally dry area , though a few patches remain in central and northern parts of the state . in contrast , most areas in the lower mississippi valley and southern great plains recorded little or no rainfall , with moderate to isolated heavy amounts limited to parts of central oklahoma , western texas , and the louisiana bayou . the rains brought regions of improvement ( but not broad - scale relief ) to western texas , including the big bend . farther north , a re - assessment of conditions led to some improvement being introduced in the texas panhandle ( especially northern sections ) and eastern parts of the oklahoma panhandle and adjacent western oklahoma . meanwhile , the dry and hot week prompted substantial deterioration across central and eastern texas , louisiana , arkansas , and ( to a lesser extent ) eastern oklahoma . as a result , moderate to severe drought became more widespread , especially in a swath from southern to northeastern texas . san antonio , tx reported just over 2 inches of rain for april - june 2018 , compared to a normal of over 10 . 6 inches ( third driest such period in 134 years of record ) . also , grass fires have become unusually common across the dallas - ft . worth metro area . in southwestern texas , to the north and northwest of laredo , a broad area of extreme drought ( d3 ) was introduced , with an area of exceptional drought ( d4 ) introduced in part of this region along the rio grande river . most of the new d3 area recorded only 2 to 4 inches of rain in the last 90 days , and 3 - month totals of only 0 . 5 to 1 . 5 inches ( with widely isolated higher amounts ) were recorded in the new d4 region .
regional climate impacts and outlook documents summarize seasonal conditions four times a year , in march , june , september and december . regions include the northeast , gulf of maine , southeast , south , midwest , great lakes region , missouri river basin , western region , alaska and northern canada , and hawaii and the pacific . select and download the most recent outlook for your region here
southeast : moderate to heavy rain ( one to several inches ) made a patchy pattern across the southeast , typical of summer thunderstorms . heavy rain was most widespread across florida while most areas in the central and eastern carolinas , northwestern alabama , and northern mississippi recorded only light rain , if any . deficient precipitation was noted on a variety of time scales in the central carolinas , leading to the introduction of abnormally dry conditions . farther west , enough rain fell to end dryness in northeastern and southwestern alabama , but dryness persisted over most of mississippi and some adjacent locales . the d0 area expanded to cover a bit more of southwester mississippi while d1 in a small part of that region remained unchanged .
alaska , hawaii , and puerto rico : in puerto rico , another relatively dry week along the southern tier kept abnormally dry conditions intact , with some expansion part of central puerto rico where rainfall deficits have begun to increase . across alaska and hawaii , existing areas of abnormal dryness remained unchanged .
for the remainder of this week ( through june 8 , 2018 ) , moderate precipitation ( 0 . 5 to 1 . 2 inches ) is forecast across a broad area in the southeastern great plains , the ohio and lower half of the mississippi river valleys , and the eastern seaboard . heavy rain ( 2 to locally 5 inches ) is forecast in southeastern texas and the southern tier of louisiana , and amounts could reach 2 inches in eastern pennsylvania and southwestern florida . farther west , moderate to heavy rain ( 0 . 5 to locally 2 . 5 inches ) is forecast for parts of the central and northeastern great plains , and far northern mississippi valley . rainfall should be light with isolated moderate totals in the rest of the country east of the rockies while little or no rain is expected from the rockies to the pacific ocean . average daily minimum temperatures should be above - normal throughout the contiguous states , with the largest departures ( 6 to 10 degrees f ) expected in the southern rockies , parts of the great basin and northern great plains , and throughout the ohio valley and northeast . daily high temperatures will not differ as far from normal , with 5 - day anomalies exceeding 3 degrees f more than normal limited to the northwest , the intermountain west , most of the rockies , the great lakes , and new england . the subsequent 5 - day period ( june 9 - 13 , 2018 ) , odds favor above - normal rainfall in central and southern sections of california , the intermountain west ( including the great basin ) , and the rockies , with surplus precipitation most likely in northern arizona . farther east , wet weather is also favored in the lower mississippi valley , most of the southeast , the southern and eastern ohio valley , and the middle atlantic states . southern alaska also has enhanced chances for above - normal precipitation . in contrast , subnormal rainfall is favored from central and southern texas northward through the plains , the western great lakes , the northern intermountain west , and the pacific northwest . temperatures are expected to average above normal across most of the contiguous states , with the exceptions of southeastern arizona , southwestern new mexico , and part of southern alaska , where cooler than normal conditions seem more likely .
percent area in continental u . s . - weekly change ( full statistics )
percent area in continental u . s . - monthly change ( full statistics )
when autocomplete results are available use up and down arrows to review and enter to select .
rcc region pages , organized by state groupings , offer links to applied climate research .
dews are partnerships of federal , tribal , state , local and academic entities within specific watersheds and / or states .
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topsoil moisture maps - the cpc produces top soil maps based on the usda data .
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lacks multi - timescale features of indices like the spi , making it difficult to correlate with specific water resources like runoff , snowpack , resevoir storage , etc .
century . the pdsi has also been widely used in tree - ring based reconstructions of past droughts in north america and other regions .
[ 1965 ] based on data from the central u . s . the sc _ pdsi performed better than the original pdsi during the 20
, 2008 ] , as the thornthwaite pe ( pe _ th ) is based only on temperature , latitude and month . this error can be minimized , however , by using the more sophisticated penman - monteith equation [ referred to as pe _ pm , which accounts for the effects of radiation , humidity and wind speed and works best over australia in a comparison of various pe formulations
[ 1965 ] chose the pe _ th mainly based on practical considerations as data for computing pe _ pm and other types of pe may be unavailable . this is especially true for global analyses .
century , comes mainly through potential evapotranspiration . as precipitation and surface air temperature are the only two climate variables with long historical records , the pdsi makes full use of these data and can be readily calculated for the last hundred years or so for most land areas . the impact of the choice of pe _ th or pe _ pm is relatively small for the 20th century , the use of pe _ th tends to overestimate the impact of the globalwarming for the model - projected 21st century climate . dai ( 2011a , jgr ) compared the various versions of the pdsi and recommended the use of the sc _ pdsi with the pe _ pm ( i . e . , sc _ pdsi _ pm ) , especially for model projections . all the references cited here can be found in dai ( 2011a , jgr ) and in the key references below . # #
data access : please cite data sources , following the data providers ' instructions .
hobbins , m . t . , a . dai , m . l . roderick , and g . d . farquhar ( 2008 ) , revisiting potential evapotranspiration parameterizations as drivers of long - term water balance trends , geophys . res . lett . , 35 , l12403 , doi : 10 . 1029 / 2008gl033840
van der schrier , g . , k . r . briffa , p . d . jones , and t . j . osborn ( 2006a ) , summer moisture variability across europe , j . clim . , 19 , 2818–2834 , doi : 10 . 1175 / jcli3734 . 1
van der schrier , g . , k . r . briffa , t . j . osborn , and e . r . cook ( 2006b ) , summer moisture availability across north america , j . geophys . res . , 111 , d11102 , doi : 10 . 1029 / 2005jd006745
van der schrier , g . , p . d . jones , and k . r . briffa ( 2011 ) , the sensitivity of the pdsi to the thornthwaite and penman - monteith parameterizations for potential evapotranspiration , j . geophys . res . , 116 , d03106
long - term pdsi over the continental us through january , 2014 . retrieved on 31 jan 2014 from urltoken
eof 1 & 2 patterns : psdi : 1900 - 2005 . ( climate data guide ; a . dai , d . shea )
eof 1 & 2 timeseries : psdi : 1900 - 2005 . ( climate data guide ; a . dai , d . shea )
acknowledgement of any material taken from this page is appreciated . on behalf of experts who have contributed data , advice , and / or figures , please cite their work as well .
visit the update bookmarks page to see the new url for more pages . if you have any questions , feel free to email us at ndmc @ urltoken .
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perpendicular recording ( or perpendicular magnetic recording , pmr ) is a technology for data recording on hard disks .

it was first proven advantageous in 1976 by shun-ichi iwasaki , then professor of the tohoku university in japan , and first commercially implemented in 2005 .

the first industry-standard demonstration showing unprecedented advantage of pmr over longitudinal magnetic recording ( lmr ) at nanoscale dimensions was made in 1998 at ibm almaden research center in collaboration with researchers of data storage systems center ( dssc ) – a national science foundation ( nsf ) engineering research center ( ercs ) at carnegie mellon university ( cmu ) .

perpendicular recording

fig . 1 illustrates an example perpendicular magnetic recording system 100 . the perpendicular magnetic recording system 100 includes a read / write head 102 , which generates a magnetic field perpendicular to a perpendicular magnetic recording stack 104 .
a book on perpendicular recording is recently published by kluwer academic press : s . khizroev and d . litvinov “perpendicular magnetic recording” , 2004
perpendicular recording : a new approach to writing on magnetic media that aligns bits vertically , perpendicular . . .
on next page we will explain how perpendicular recording works and we will compare it to longitudinal recording .
reproduced voltage versus linear bit density characteristics for perpendicular magnetic recording with various recording layer thickness , δ .
fig . 1 is a schematic representation of a perpendicular magnetic recording system with a prior art patterned perpendicular medium .
perpendicular recording is a method of recording data to a hard disk drive ( hdd ) . perpendicular recording aligns data bits vertically — perpendicular to the disk , which allows for additional room on a disk to pack more data , thus , enabling higher recording densities . contrast with longitudinal recording .
perpendicular magnetic recording systems , such as systems including a perpendicular recording head and a perpendicular magnetic recording stack with a coupled granular / continuous ( cgc ) structure having a dual continuous layer , can exhibit ultra high density recording capability resulting in an increased storage capacity .
the above analysis of both the tilted perpendicular recording and the perpendicular recording based on micromagnetic simulations suggests that , the tilted perpendicular recording system can significantly increase the medium thermal stability as compared to both the longitudinal and the perpendicular recording . for example , a possible gain in stability from 50 % to about 100 % may be achieved over the perpendicular recording . a feasible smaller transition parameter and a larger snr can be achieved in the tilted perpendicular recording than the perpendicular recording . an almost instantaneous switching in the tilted medium is obtained in the tilted perpendicular recording . this switching may be used to achieve a data rate above 2 ghz . the tilted recording system has much less fringing problem as compared to both the longitudinal and the perpendicular recording .
the perpendicular recording system is suitable for high density recording because of the strong magnetic coupling between neighboring magnetic bits .
the invention is also a magnetic recording disk drive that incorporates the above - described patterned perpendicular magnetic recording disk .
fig . 2 illustrates an example perpendicular magnetic recording stack having a dual continuous layer .
4 . the perpendicular magnetic recording medium of claim 1 , wherein the interlayer comprises ru .
information may be stored on a perpendicular magnetic recording stack . such information may be written to and / or read from the perpendicular magnetic recording stack using a read / write head .
considering the evolution to the novel perpendicular magnetic recording , i particularly examined the complementary relation to conventional longitudinal recording , which is the complementary nature between the two recording modes .
perpendicular ( solid lines ) and in - plane ( broken lines ) hysteresis curves of co - cr perpendicular recording media with various cr contents .
year - by - year trend of the number of papers related to perpendicular magnetic recording for journals of the ieee magnetics society , and for the perpendicular magnetic recording conference ( pmrc ) .
the present tapered write head designs and the tilted perpendicular recording media are in part based on recognition of certain technical limitations of the in longitudinal and perpendicular recording systems with conventional write heads .
the following sections first describe examples of tapered single pole write heads and titled perpendicular recording media . next , certain limitations of longitudinal and perpendicular recording systems with conventional write heads are discussed to illustrate some of the advantages and benefits of the combinations of the tapered single pole write heads and titled perpendicular recording media . in addition , various designs of tapered single pole write heads are described . such tapered single pole write heads may be used with various perpendicular recoding media including the tilted perpendicular recording media as illustrated in the specific examples in this application and non - tilted perpendicular recording media such as various perpendicular recording media .
flux flow in a double - layered perpendicular magnetic recording medium . horseshoe - shaped bits are formed with the perpendicular and in - plane anisotropy films .
3 . the perpendicular magnetic recording medium of claim 1 , wherein the magnetic layer comprises cocrpt .
however , as the perpendicular recording components were developed , numerous disadvantages were discovered . here is a list of some of the disadvantages of the perpendicular system :
in a perpendicular recording media , magnetization is formed easily in a direction perpendicular to the surface of a magnetic medium such that bits stand up and be perpendicular to surface , resulting from perpendicular anisotropy in the magnetic recording layer . on the other hand , in a longitudinal recording media , magnetization is formed in a direction in a plane parallel to the surface of the magnetic recording layer , resulting from longitudinal anisotropy in the magnetic recording layer .
fig . 5 shows simulation results of the a m - h loop for typical perpendicular recording media .
due to at lest the above reasons , the thermal stability is a problematic in the perpendicular recording .
5 . the perpendicular magnetic recording medium of claim 1 , wherein the interlayer comprises and metal oxide .
fig . 3 illustrates example operations for manufacturing a perpendicular magnetic recording stack having a dual continuous layer .
the long argument between longitudinal and perpendicular recording was settled at last . it can be said that it was a moment at which the true value of perpendicular magnetic recording was recognized for the first time widely and to a great degree . for this very reason , the strong impetus for development of perpendicular recording resumed .
perpendicular recording is the hard drive industry ' s answer to the superparamagnetic effect . as its name implies , perpendicular recording aligns bits vertically—perpendicular to the disk surface . this recording method allows drive manufacturers to increase a disc ' s areal density without shrinking bits to a point where they become vulnerable to the superparamagnetic effect .
fig . 2 illustrates an example perpendicular magnetic recording stack 200 having a dual continuous layer . in one implementation , the perpendicular recording stack 200 includes a substrate 202 , an underlayer 204 , a magnetic granular recording layer 214 , a dual continuous layer 224 , and an overcoat 230 . however , the perpendicular magnetic recording stack 200 may have more or less layers .
perpendicular recording technology achieves 1 . 8 - inch drive that holds the industry largest 80 - gigabytes of information
the structure of perpendicular pole head with soft underlayer provides an immediate advantage of perpendicular recording over longitudinal : the magnitude of the recording field in this configuration is increased by approximately a factor of 2 over longitudinal medium .
fig . 3 illustrates example operations 300 for manufacturing a perpendicular magnetic recording stack having a dual continuous layer .
this invention relates generally to patterned perpendicular magnetic recording media , such as disks for use in magnetic recording hard disk drives , and more particularly to patterned disks with data islands having improved magnetic recording properties .
one advantage for the perpendicular recording is that the medium thickness can be larger than that in the perpendicular recording . however , as the recording densities increase , the medium thickness of the perpendicular recording is also limited . large thickness medium can cause the write field to decrease . this decrease is undesirable because it limits the h k of the medium that can be written on .
, it is readily apparent that demagnetization caused by random thermal fluctuation is very much suppressed in perpendicular magnetic recording .
read - back resolution of perpendicular recording medium is lower compared with longitudinal medium due to the presence of sul .
2 . longitudinal recording system ( conventional ) recorded magnets repulse and weaken each other in longitudinal recording .
in the storage device industry to commercialize perpendicular magnetic recording , and the company has applied the technology to hdd that achieve unsurpassed recording density and high operating reliability . this success rests on development of a new magnetic disk structured to support perpendicular recording , a new high performance perpendicular magnetic head , and disk and head integration technology that maximizes their combined performance .
in the longitudinal recording , the medium coercivity h c is approximately in the range of between 0 . 5 hk and 0 . 6 h k due to the perpendicular component of the write field at the tips and boundaries from the write poles . in the perpendicular recording , the medium h k is in the perpendicular direction . the largest component of write field from single pole head with sul is also in the perpendicular direction , parallel to the medium anisotropy . as can be seen in fig . 4 , for same h k media , a larger write field is required in the perpendicular recording as compared to the longitudinal recording . by doing so , the values of h k for perpendicular media that can be written in the perpendicular recording are not much higher than the longitudinal recording .
the figure shows how recorded magnetization changes according to the thermal fluctuation as the recording density is increased . with longitudinal recording , recording bits become increasingly unstable as the recording density is increased , in contrast , in perpendicular magnetic recording , the recorded magnetization becomes more stable at high densities . this is a typical difference derived from inherent essential natures of the two recording modes . as a consequence , it can be concluded that perpendicular recording is fundamentally appropriate for high - density recording . in perpendicular magnetic recording , the head and disk strongly interact with each other , which brings stability against ambient circumstance such as temperature and air pressure , which in turn affects spacing of the head and medium .
after these experiments , i once more inferred that two possibilities would become particularly important in the future of perpendicular magnetic recording .
this application provides , among others , perpendicular magnetic recording systems that use tapered single pole write heads . suitable magnetic recording media include tilted perpendicular recording media where the anisotropy directions of a layer of magnetic grains for recording are tilted from the direction perpendicular to the layer , and non - tilted perpendicular recording media where the anisotropy directions of a layer of magnetic grains for recording are substantially perpendicular to the layer without tilting . the tapering of the single pole write heads may be designed to produce large down - track field strength and field gradient to produce sharp transitions in writing data and to produce large off - track field gradient to avoid erasure of neighboring tracks in high density media .
the recording medium is characterized by the recording layer thickness , distance between recording layer and the soft underlayer and the thickness of the soft under - layer . each of the head and media parameters influences the recording process .
prototyping of a hard disk drive using perpendicular magnetic recording ( 52 . 5 gb / in 2 ) and its recording bit image on the disk , by hitachi ltd . 15 )
fig . 7b shows simulation results of the medium switching field distribution along the center track for the perpendicular and longitudinal recording media .
what is needed is a patterned perpendicular magnetic recording medium that has a narrow sfd and is less susceptible to adjacent track overwrite .
during that work , it became clear to me that the increase of recording density was most important for research on magnetic recording . the invention of metal tape described above and the establishment of the theory of high - density magnetic recording were both achievements along that path of development . moreover , i had noticed by 1975 that magnetization perpendicular to the plane of the recording medium was an extremely effective means to improve the recording density . 3 ) , 4 ) these speculations and four discoveries are shown as major milestones in the early research on perpendicular magnetic recording that guided the beginning of perpendicular magnetic recording , as the following .
fig . 9 shows simulation results of the switching field distribution with respect to the write field angle for the titled perpendicular media and conventional perpendicular media .
fig . 10 shows simulation results of the switching speed as a function of the damping constant for both the titled perpendicular media and conventional perpendicular media .
magnetic recording traditionally uses a longitudinal recording method where a recording medium is configured to have its anisotropy easy axes along the longitudinal directions within the magnetic recording medium plane . the storage density based on this method is known to be limited due to the thermal instability of the magnetic grains . an improved method based on a perpendicular recording configuration has been developed to mitigate some technical limitations in the longitudinal recording devices , e . g . , to achieve better thermal stability than the longitudinal recording . typically , a perpendicular recording configuration uses media with their medium anisotropy easy axes perpendicular to the medium plane and a single pole head with a soft magnetic under layer to enhance the write field . another magnetic recording technique called “tilted longitudinal recording” has also been developed to use an inductive head with a tilted medium .
fig . 7a shows simulation results of the spatial profiles of the perpendicular field , filed angle , and the medium coercivity relative to the field anisotropy along the center track of the perpendicular and longitudinal recording media .
in one embodiment , the invention generally provides a perpendicular recording medium comprising a magnetic layer , wherein the magnetic layer exhibits improved corrosion resistance while maintaining the magnetic properties suitable for high density perpendicular recording . one embodiment provides a perpendicular recording medium comprising a magnetic layer , wherein the magnetic layer comprises cobalt ( co ) , platinum ( pt ) , and at least one of molybdenum ( mo ) and chromium ( cr ) , the magnetic layer having perpendicular magnetic anisotropy . another embodiment provides a granular perpendicular recording medium comprising a granular magnetic layer , wherein the magnetic layer comprises co , pt , and at least one of mo and cr , the granular magnetic layer having perpendicular magnetic anisotropy .
comparison of longitudinal and perpendicular recording can be found in : h . n . bertram and m . williams “snr and density limit estimates : a comparison of longitudinal and perpendicular recording” – ieee trans . magnetics , vol . 36 , pp . 4 - 9 , 2000
fig . 1 illustrates an example of a single pole write head for writing on a titled or non - titled perpendicular recording medium .
can be derived with respect to the magnetic head , recording medium , signals , and recording method . this complementarity relation
this comparison of normalized roll - off curves is not completely honest – it is difficult to achieve a longitudinal pw50 as narrow , as the ones which be obtained with perpendicular recording . assuming the same pulse width can be achieved , the perpendicular recording has intrinsically lower resolution .
magnetic flux distribution of a perpendicular head in an enlarged model experiment . this photograph appeared on the cover of a magazine , nikkei electronics , of august 7 , 1978 , 5 ) which reported perpendicular magnetic recording .
fig . 4 shows simulation results of the angles of media coercivity fields with respect to media anisotropy in both perpendicular and longitudinal recording systems .
2 . the perpendicular magnetic recording medium of claim 1 , wherein the magnetic layer comprises argon ions on a surface of the magnetic layer .
fig . 8 also shows that the nucleation field of the tilted medium , defined as the negative field with the first medium grain reversed , is also much larger ( than that of the perpendicular medium . the absolute value of hn for tilted perpendicular media is smaller than that for the perpendicular media , the ratio of abs ( hn / how ) for tilted perpendicular recording media is much larger than that for conventional perpendicular recording media . based on the data in fig . 8 , in the illustrated tilted perpendicular recording medium , this ratio is about ( 0 . 4 / 0 . 65 ) = 0 . 61 while the ratio for the conventional perpendicular recording medium is about ( 0 . 6 / 1 . 35 ) = 0 . 44 . this implies less medium noise and larger thermal stability in both the high density and the low density recording .
the first data of recording magneto - motive force versus reproduced output characteristics of a double - layered perpendicular medium and a single - pole head in comparison to a single layer perpendicular medium ( may 19 , 1978 ) .
fig . 5 is a schematic of the write process on patterned perpendicular media .
is seagate ' s barracuda 7200 . 10 as good as it sounds ? and what ' s the deal with perpendicular recording technology , anyway ?
the storage capacity of a perpendicular magnetic recording stack may be improved by increasing the areal density of a magnetic granular recording layer . however , as the areal density of a magnetic granular recording layer increases , other performance factors may become more relevant , including without limitation the thermal stability of the magnetic granular recording layer , recording ease ( i . e . , writability ) , and media noise .
. therefore , it is very structure - oriented . for the perpendicular magnetic recording , in contrast , because its resolution depends entirely on the playback head resolution , the smallest bit on the recording layer can be formed as small as the size of fine grains of the magnetic film . perpendicular magnetic recording can be said to be more material - oriented .
in perpendicular magnetic recording , because the bit magnetization is aligned in an anti - parallel way , the recording bits are mutually attracted with respect to the magnetic force , which allows them to be packed densely to produce a highly dense configuration . in similar fashion , because the head and medium are also mutually attractive , the writing head field distribution becomes steeper and more focused as the medium approaches the head . for that reason , a narrow track recording is readily realized . it can attain a high linear recording density and can simultaneously accommodate even a narrow track recording . therefore , the areal recording density is more easily increased using perpendicular recording than using longitudinal recording . 13 )
the answer is simple : nobody knows for sure . the history of perpendicular recording started many decades ago , almost simultaneously with longitudinal recording . many attempts have been made to develop a perpendicular recording system , however the industry was successfully introducing new generations of longitudinal components , achieving high areal density . the development of high density systems required complicated optimization of recording heads and media , consuming efforts of large groups of scientists and engineers . the few parts , which were produced never demonstrated any advantages over longitudinal recording components . the research in perpendicular recording was left to several university groups and was not considered to be worth much of attention .
in the above examples of the tilted perpendicular recording , tapered single pole write heads are used to produce large down - track field and field gradient and to generate a large off - track field gradient . in addition , the tapering effectively reduces the footprint of the write pole on the recording media and thus allows for higher data densities . these and other desirable properties of the tapered single pole write heads may be used to improve performance of other perpendicular recording media such as non - tilted perpendicular recording media where the anisotropy axes of the magnetic grains are substantially perpendicular to the media surface .
a single pole head with the sul and the tapered neck with a small throat height can achieve large perpendicular recording field with large field gradient . in the perpendicular recording , the medium coercivity decreases with the write field . the effective write field gradient is small . in the present tilted perpendicular recording , the recording system can be optimized with respect to the medium tilted angle so that the direction of the optimum recording field at the transition center can be close to 45° with respect to the perpendicular direction . therefore , close to the transition center where the largest perpendicular field gradient occurs , the medium coercivity increases with decreasing write field . under these conditions , a large effective field gradient is produced and thus the medium transition parameter can be reduced .
thermal stability of recording bits of a hard disk drive , indicating that the higher the density of perpendicular magnet recording , the less the decrease the stability becomes , thereby showing sufficient stability , by toshiba . 17 )
7 . the perpendicular magnetic recording medium of claim 1 , the magnetic layer comprising cobalt , platinum , and at least one of molybdenum and chromium .
. however , what i found is that another mode exists in which we can align magnets perpendicularly to the tape plane , as depicted in ( b ) of the figure . this is the ‘perpendicular mode’ , or perpendicular magnetic recording .
the idea of perpendicular magnetic recording came to my mind first and foremost when i considered the possibility of using the perpendicular component of the magnetization directly for high - density magnetic recording because it always appeared in the pursuit of high - density recording , as described above . in the following , i will describe the early experiment that made me think of that idea ( see
the majority of hard disk drives found on the market today use a recording technology called longitudinal , where bits are stored side by side on the magnetic surface . this recording technique has been used since the first hard disk drives . a new recording technology , called perpendicular , is being used on newer hard disk drives , allowing a higher recording density . in this tutorial we will explain you everything you need to know about perpendicular recording and how data is stored on the hard disk drive magnetic surface .
the breakthrough that transcended this areal density limitation was perpendicular magnetic recording . the dotted line in the figure marks the density trend of perpendicular magnetic recording . it extends the trend more than 100 gbit / inch 2 with a linear development , possibly entering into the terabit density domain . the fact that the trend of perpendicular recording shows a linear line throughout the entire period from the experimental age to the actual mass - production age proves that the combination of the principle and its associated devices to achieve high - density recording was correct .
s ince the first time
get perpendicular
got stuck in our heads , we ' ve anxiously anticipated the arrival of perpendicular recording technology . the wait has been long , especially on the desktop , but perpendicular recording has finally arrived in seagate ' s barracuda 7200 . 10 hard drive . and it ' s arrived in style . seagate has exploited the new recording technology to offer a drive with a monstrous 750 gb capacity—50 % more than any other drive on the market .
lee , k . j . , et al . ,
recording physics of perpendicular recording with single layered medium and ring head ,
journal of applied physics , 91 ( 10 ) : 8700 - 8702 , may 2002 .
3 . the magnetic recording head as in claim 1 , wherein the tapered neck has a straight profile along tracks on the recording medium .
the shape of the perpendicular recording signal read - back also depends on the track width . the narrower the recorded track , the less is the field cancellation effect ( fce ) and the read - back waveform is closer to rectangular . this is easily understood from the fact that for perpendicular recording media both down - track and cross - track directions are equivalent ( they are perpendicular to the medium magnetization direction ) .
figs . 2a , 2 b , 3 a , and 3 b show two examples of tapered single pole write heads and an example of titled perpendicular recording media .
iwasaki , s . ,
perpendicular magnetic recording ,
ieee transactions on magnetics , mag - 16 ( 1 ) : 71 - 76 , jan . 1980 .
an example of a tilted perpendicular magnetic recording medium is also described to include a magnetic layer and a soft magnetic under layer beneath the magnetic layer . the magnetic layer includes magnetic grains with anisotropy easy axes tilted with respect to a perpendicular direction that is perpendicular to the magnetic layer . when combined with a tapered single pole write head , such a recording medium may provide better recording performance than other recording systems , such as improved thermal stability , a higher anisotropy field h k , smaller switching field distribution , reduced noise , and faster switching speed . high storage densities above 10 2 gbits / in 2 , e . g . , at the level of tbits / in 2 , can be obtained in such a tilted perpendicular recording system .
the medium 102 has a structure for perpendicular recording and may be implemented as a tilted perpendicular medium or a non - tilted perpendicular medium . the medium 102 may be a disk having multiple layers formed on a substrate . as one example , the medium may include a magnetic medium layer , a growth layer beneath the magnetic medium layer , and a soft under layer beneath the growth layer . as an example of the non - tilted perpendicular recording media , the magnetic medium layer may include magnetic grains that are grown along the perpendicular direction and have their anisotropy directions in the perpendicular direction . alternatively , the magnetic medium layer may include magnetic grains that are grown along the perpendicular direction but have their anisotropy directions tilted at a predetermined angle or angles with respect to the perpendicular direction . a tilted perpendicular medium may also be constructed to have at least one magnetic layer with perpendicular anisotropy between two magnetic exchange coupling or anti - ferromagnetic coupling layers . the magnetic interactions of these layers produce an effective tilted anisotropy of the multi - layer structure . two or more such multi - layer structures may be stacked .
perpendicular media grains are strongly oriented . this results in smaller medium noise and a sharper recorded transition . the high orientation of the perpendicular medium also improves side - track writing and edge noise .
fig . 8 shows simulation results of the remanent m - h loops for the titled perpendicular media and conventional perpendicular media where the cone angle distribution for the anisotropy axes is within 3 degrees .
the next important development was the perpendicular recording medium . a medium material was required for which the magnetic surface poles of n and s were retained on the surface plane , which is designated as a perpendicular anisotropy film . we found in 1975 that a thin film made of cobalt ( co ) and chromium ( cr ) alloy was the most promising perpendicular medium material . luckily enough , that material was available as a result of research work of magneto - optical recording , which was being conducted parallel in our laboratory at that time . this finding ultimately created the most effective means of accomplishing perpendicular magnetic recording .
figs . 7a - 7e are sectional views of a single discrete magnetic island on a patterned perpendicular magnetic recording medium for different implementations of the medium according to this invention .
6 . the perpendicular magnetic recording medium of claim 1 , wherein the magnetic layer comprises a co - containing magnetic material that forms less than 10 atomic percent coox in the co - containing magnetic material after exposure of the perpendicular magnetic recording medium to an environment having 80 % relative humidity at 80 degree c . for at least four days .
magnetic recording hard disk drives with patterned magnetic recording media have been proposed to increase data density . in conventional continuous magnetic recording media , the magnetic recording layer is a continuous layer over the entire surface of the disk . in patterned media the magnetic recording layer on the disk is patterned into small isolated data islands arranged in concentric data tracks . patterned - media disks may be longitudinal magnetic recording disks , wherein the magnetization directions are parallel to or in the plane of the recording layer , or perpendicular magnetic recording disks , wherein the magnetization directions are perpendicular to or out - of - the - plane of the recording layer . perpendicular media will likely be the choice for patterned media because of the increased data density potential of perpendicular media . to produce magnetic isolation of the patterned data islands , the magnetic moment of the spaces between the islands are destroyed or substantially reduced to render these spaces essentially nonmagnetic . alternatively , the media may be fabricated so that that there is no magnetic material in the spaces between the islands . u . s . pat . no . 5 , 820 , 769 describes a type of patterned perpendicular media and its fabrication method .
magnetic recording techniques , devices , and systems under a tilted perpendicular recording configuration . an implementation of such a system may include a magnetic head having a single pole to produce a magnetic field along a perpendicular direction ; and a storage medium having a top surface to be substantially perpendicular to the perpendicular direction and positioned to interact with the magnetic field , wherein the storage medium includes ( 1 ) a magnetic medium layer that has anisotropy easy axes tilted at a tilting angle with respect to the perpendicular direction , ( 2 ) a growth layer beneath the magnetic medium layer , and ( 3 ) a soft under layer beneath the growth layer .
therefore , the roll - off ( amplitude versus recorded density ) behavior of the perpendicular system is quite complicated with signal shape and amplitude depending on numerous factors , such as recording density , track width , sul thickness , distance to the sul etc . intrinsically larger amplitude of the perpendicular signal at lower densities rolls off faster at higher recording density . therefore , it is not clear how to estimate gains and losses of the perpendicular system read - back . also , it is very difficult to compare perpendicular read - back signal with longitudinal .
perpendicular prml channels were described in : m . madden . m . oberg , z . wu and r . he “read channel for perpendicular magnetic recording” – ieee trans . magnetics , vol . 30 , pp . 241 - 246 , 2004 r . cidecian , e . eleftheriou and t . mittelholzer “perpendicular and longitudinal recording : a signal processing and coding perpective” – ieee trans . magnetics , vol . 38 , pp . 1698 - 1704 , 2002
prior to the perpendicular method , the bits were written horizontally on the recording surface of the disk platter . ( assistance with these illustrations courtesy of hitachi global storage technologies . )
a higher recording field is very advantageous for magnetic recording . not only does the cylindrical structure of perpendicular medium grains provide better thermal stability , the ability to overwrite high coercivity medium allows higher anisotropy and improves thermal stability even further . also , the higher coercivity medium has a smaller transition parameter and allows recording at higher linear density .
looking back at how the perpendicular anisotropy magnetic film was found , the major factors were the following .
shielded pole heads are becoming popular in perpendicular recording . the idea is to place a high permeability shield next to the recording pole . this shield “sucks” some of the head flux and improves the head gradient , while slightly reducing the deep gap field . the shielded head has an additional advantage – a larger horizontal magnetic field component helps to switch perpendicular media .
generally , lowering exchange coupling of perpendicular recording media causes their magnetic hysteresis loops to become more sheared , and correspondingly have a larger difference between coercive field ( hc ) and nucleation field ( hn ) . there are many prior examples of this relationship between exchange coupling and hc - hn for cocr - based and reactive oxygen - based sputtered perpendicular recording media .
7 . the magnetic recording head as in claim 1 , wherein the single - pole magnetic write tip comprises a plurality of magnetic layers along the direction substantially perpendicular to the recording medium , wherein two adjacent magnetic layers have equilibrium magnetizations in substantially opposite directions .
in one implementation , the perpendicular magnetic recording stack 104 includes a substrate 106 , one or more underlayers 108 , one or more magnetic granular recording layers 110 , and a dual continuous layer including a first continuous layer 112 and a second continuous layer 114 .
in america , at around 1982 , several venture companies of perpendicular recording had been founded . in a similar fashion , from around 1985 , american universities started supporting magnetic recording research centers one after another . i believe that happened because of the impact of our 144 committee on magnetic recording in japan society for the promotion of science ( jsps ) , which was described above in section 3 . subsequently , ibm proposed a new read head using the magneto - resistive ( mr ) effect , which produced a separate stream from perpendicular recording in the roadmap , however even during that time , our committee continued steadily with its activities to promote perpendicular recording ; now we have had meetings more than 190 times .
hitachi will present these achievements at the 8th perpendicular magnetic recording conference ( pmrc 2007 ) , to be held 15th - 17th october 2007 , at the tokyo international forum in japan .
as the technology progressed , it has become clear that the thermal stability gains are smaller than expected , but there are many other , less evident advantages of the perpendicular recording scheme .
the numerous theoretical predictions and experimental evaluations of the perpendicular recording potential are all over the place . the most optimistic scenarios predicted that the optimized perpendicular system may achieve a factor of 4 - 5 over the best longitudinal areal density , resulting in approximately 500 gb / in2 . pessimistic evaluations consider that the advantages of the perpendicular recording are compensated by the disadvantages , resulting in the complete wash - out between the longitudinal and the perpendicular schemes . the realistic estimates are in the range of doubling the areal density achievable with longitudinal media , around 200 - 300 gb / in2 .
talking to people of hitachi gst , fujitsu , hitachi , and toshiba , they say that about 75 % of hard disk drive shipments will be of perpendicular products . in 2010 , probably all such products requiring memory will have adopted perpendicular recording drives . in this way , such large companies as toshiba , hitachi , fujitsu , and seagate technology are all concentrating on producing perpendicular disk drives .
for example , one of such problems is the thermal stability . as the recording densities increase , due to the constraint caused by the thermal stability , the track width decreases faster than both the down track and the perpendicular dimensions . the perpendicular recording write field decreases faster with the track width as compared to the longitudinal recording . although the tapered neck structure with a very small throat height on the write pole may be used to increases the write field significantly , the total write field still decreases when the recording density increases .
the tilted perpendicular recording design shown in figs . 2a and 2b can be used to produce large write fields and thus provide improved recording performance than conventional longitudinal recording and perpendicular recording . in order to enhance the write field magnitude , the write pole tip is designed to have a tapered neck structure with a very small throat height . the medium is designed to have the anisotropy easy axes tilted at a desired angle , e . g . , 30° or 45° , with respect to the perpendicular direction . the medium easy axes may be parallel to one another with a small cone angle of , for example , 5° or less .
the industry highest recording density in commercially available as of december 14 , 2004 .
a read head for detecting the magnetized recording layer structure on the pillar tops .
due to above reasons , it is difficult for both the longitudinal recording and the perpendicular recording to exceed areal densities higher than 200 gbit / in 2 . one of the main limitations in these systems is the low write field produced by various conventional write heads and thus media with a high medium anisotropy cannot be used to improve the recording performance .
the above tilted perpendicular recording may be used to achieve a high write field from write head to write highest anisotropy magnetic media . the media h k may be increased by a factor of about 1 . 6 with this method . the neighboring tracks becomes more stable as the hk of the media increases . a larger write field , almost 50 - 80 % higher than the highest write field in other systems , may be used in the present system . this high h k can be used to significantly solve thermal stability problem . for example , if the current grain sizes in other magnetic media are used , the tilted recording media may have an extreme long data decay time and can be practically used to store written data indefinitely . the media switching field distribution can be decreased by 80 % . the switching speed , which may be at least 5 times faster than that in the perpendicular recording , is comparable with longitudinal recording . the tilted perpendicular recording allows for a large write field , almost 50 - 80 % higher than the highest write field in other systems . for example , the write field can be close to the saturation field bs by introducing the tapered neck structure with very small throat height for single pole tip ( spt ) with sul . the tilted perpendicular recording significantly reduces the media switching field distribution so that a sharp transition can be achieved with a small transition width . this leads to a higher storage linear density . the tilted perpendicular recording also increases the media energy barrier at the track edge and the neighboring tracks as compared to conventional perpendicular recording . this allows for a reduction in the erase band by 50 % or more in comparison with other recording methods . notably , a storage density at or above 1 tera bit / in 2 may be achieved in systems under this tilted perpendicular recording configuration . the tilted perpendicular recording may be suitable for various recording applications such as hard disk recording , pattern media , thermal assistant ( pattern ) media and other magnetic recording applications .
a perpendicular magnetic recording stack with a dual continuous layer and a method of manufacturing the same . the perpendicular magnetic recording stack includes a substrate , one or more magnetic granular recording layers , and a dual continuous layer having first and second continuous layers . the first continuous layer , disposed between the second continuous layer and the magnetic granular recording layers , has an intermediate lateral exchange coupling , which is higher than the lateral exchange coupling of the magnetic granular layers . the second continuous layer has a higher lateral exchange coupling than the first continuous layer .
a straightforward argument from the vertical field estimate is that the perpendicular pole head can in principle write media with twice the coercivity of the longitudinal medium . however , the realistic gain is much smaller due to different switching processes of longitudinal and perpendicular media . longitudinal grains have larger dispersion of easy axis orientation and are easier to switch , while perpendicular grains are typically well oriented in the vertical direction . in practice , the coercivity gain of a perpendicular recording system over longitudinal medium may be close to 50 - 70 % .
6 . the magnetic recording head as in claim 4 , wherein the tapered neck has a straight profile on a trailing edge along the tracks of the recording medium .
referring back to fig . 8 , the medium h k ( h n ) in the tilted perpendicular recording system is significantly larger than the medium h k ( h n ) in the perpendicular recording . in the cross track direction , any in - plane field changes the angle between the write field and the medium anisotropy direction away from 45° . as shown in fig . 4 , the energy barrier of the medium grains increase with this angle . as go off track , the energy barrier increases . both the h k increases and the angle changes in the tilted perpendicular recording increase the energy barrier of the medium grains in the neighboring tracks . as a result , the adverse effect of the fringing field from the write head is reduced in the tilted perpendicular recording .
iwasaki , s . ,
perpendicular magnetic recording focused on the origin and its significance ,
ieee transactions on magnetics , 38 ( 4 ) : 1609 - 1614 , jul . 2002 .
implementations described and claimed herein provide perpendicular magnetic recording stacks with a dual continuous layer . in one implementation , the perpendicular magnetic recording stack includes a substrate , one or more magnetic granular recording layers , and a dual continuous layer having first and second continuous layers . the first continuous layer , disposed between the second continuous layer and the magnetic granular recording layers , has an intermediate lateral exchange coupling , which is higher than the lateral exchange coupling of the magnetic granular layers . the second continuous layer has a higher lateral exchange coupling than the first continuous layer .
a method of digital recording on a magnetic disk in which the bits are in a vertical arrangement instead of horizontal in order to take up less space . also called
vertical recording ,
toshiba and seagate introduced perpendicular recording drives in the 2005 - 2006 time frame . other drive vendors followed , and areal densities reached 400 gigabits per square inch by 2009 .
the demagnetization field in the perpendicular medium is small at the transition region . this allows writing narrower magnetic transitions and improves thermal stability of high density data ( this is opposite to longitudinal medium ) . also , the non - linear transition shifts in the perpendicular medium are less critical , compared with longitudinal recording .
in may 2005 , toshiba ( japan ) announced the shipment of a new music player with an installed hard disk drive , which for the first time in the world , used perpendicular magnetic recording . it was in 1977 that i first presented perpendicular magnetic recording at the international magnetic conference in los angeles . therefore , it took all of 28 years until that technology first appeared in the marketplace .
perpendicular flexible disk drive with a co - cr / ni - fe double layered recording medium and a single pole head . the auxiliary magnetic pole was located on the rear side of the disk .
the prior perpendicular recording is also limited by the signal to noise ratio ( snr ) due to the media switching field distribution , the small write field gradient , and effect of the magnetostatic interaction .
table 1 compares magnetic properties and recording parametric for perpendicular magnetic recording stacks having a single continuous layer with perpendicular magnetic recording stacks having a dual continuous layer . the magnetic properties include : coercivity field , h c , nucleation field , h n , and magnetization thickness product , mrt . the recording parametric include : writing plus erasure , wpe , reverse over - write , rev _ ow , on track bit error rate , pe , off track bit error rate , otc , media signal noise ratio , esmnr , and total signal noise ratio , esnr . as shown in table 1 , the dual continuous layer improves the magnetic properties and recording parametric .
signal processing for readback signals has been changed . that is simply a matter of course because longitudinal recording was fundamentally appropriate for analog signals . therefore , standing on the concept of ‘complementarity’ , which means the accomplishment of a total world by adding perpendicular recording to the conventional longitudinal recording world , is important . this is not a concept of ‘duality’ or a dual entity .
with reproduced waveforms indicating a single - peaked pulse resembling that of a conventional recording .
4 . the magnetic recording head as in claim 1 , wherein the tapered neck has a third tapered profile on a leading edge along the tracks of the recording medium .
5 . the magnetic recording head as in claim 4 , wherein the tapered neck has a fourth tapered profile on a trailing edge along the tracks of the recording medium .
base layers , i . e . all layers lying under the first magnetic recording layer
perpendicular recording can enhance the thermal stability in comparison with longitudinal recording . as the areal density increases , the medium grains in the down track and cross track dimensions are decreased in order to maintain good signal to noise ratio ( snr ) . so the only way to enhance thermal stability for a given anisotropy medium is to increase the medium thickness . for a medium thickness greater than the grain diameter , the medium anisotropy directions are more likely to have perpendicular component as the thickness of the medium increases . however , there are still some intrinsic problems in perpendicular recording that cannot be easily solved satisfactorily .
the difference between longitudinal and perpendicular recording is the orientation of the media grains . in the case of longitudinal recording the grains magnetization is lying in the plane of the magnetic medium . when the media is magnetized by the recording head , the average magnetization is pointing in the down - track direction ( figure 7 . 1 ) . when perpendicular head and media are used , the media grains are oriented in the “depth” of the medium and their magnetization is pointing either “up” or “down” .
once again , it is worth noticing , that the particular perpendicular roll - off curve strongly depends on the head and medium optimization . with all the advantages , draw - backs and limitations of the perpendicular recording system , recent experimental studies demonstrated about a 20 - 40 % gains in the highest achievable areal density .
the principle of conventional magnetic recording is that magnetic fields are applied parallel to the plane of the magnetic medium . as described in this paper , the invention and development of a new method of placing the magnetized information perpendicular to the plane of the magnetic recording medium is presented . the yield in the mass production of high - density hard disk drives ( hdds ) for perpendicular recording is much higher than that of hdds for conventional recording . consequently , it is estimated that as many as 75 % of the 500 million hdds to be shipped this year will use this technology .
victora r . ( 2001 ) perpendicular recording media . in : plumer m . l . , van ek j . , weller d . ( eds ) the physics of ultra - high - density magnetic recording . springer series in surface sciences , vol 41 . springer , berlin , heidelberg
to understand the “u” - shape , we have to analyze the structure of the stray fields in the case of perpendicular recording . the schematic diagram of these fields is shown in figure 7 . 10 .
these recording techniques , however , have difficulties to address various limitations or barriers for further increasing the storage densities , such as the thermal stability issue , the medium noise , the bit error rate limitations , and the limited data rate due to the limited medium switching speed and other limitations . the thermal stability issue is particularly limiting in the longitudinal recording . the large media switching field distribution and transition width can lead to certain limitations in the perpendicular recording in addition to the limitation due to the media switching speed problem . in both longitudinal and perpendicular recording , the write field decreases with track width and this aspect of such methods limits the storage densities . furthermore , the fringing field and the erase of neighboring tracks in both longitudinal and perpendicular recording are also barriers to achieving high storage densities .