bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of spin–orbit interaction on the electrical conductivity of three‐dimensional disordered systems
Authors: Spisak B. J. , Paja A. , Morgan G. J.
Published: May 2005

A calculation of the effects of spin–orbit interaction on electron transport in 3D disordered systems is presented. We use the Wigner density matrix to construct self‐consistent transport equations which can be used to discuss weak localization (quantum interference) effects and even strong localization. The formula for the transport relaxation time has been obtained. The change of the resistivity due to spin–orbit interaction is negative in agreement with experiment. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chirality effect on carbon nanotube electron resonators
Authors: Yang Linfeng , Chen Jiangwei , Yang Huatong , Dong Jinming
Published: May 2005

The quantum conductance oscillations of metallic single‐walled carbon nanotube (SWNT) electron resonators with different chirality have been studied numerically. It is found that the slow oscillation background as well as fast conductance oscillations are intrinsic properties of SWNT electron resonators. All metallic SWNT except zigzag type electron resonators can present slow conductance oscillations background, whose oscillation period is increase as the chiral angle decrease, and the zigzag type SWNT resonators don't show the slow oscillation background. For the armchair SWNT resonators the slow oscillation background have distinctly different transport behavior depending on whether the length of the tube is commensurate with a (3N + 1) rule, with N the number of basic carbon repeat units along the nanotube length. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigation on the magnetic and electronic properties of Sr2BMoO6 (B = Fe, Co)
Authors: Xiang H. P. , Wu Z. J. , Meng J.
Published: May 2005

Sr2FeMoO6 and Sr2CoMoO6 were studied by use of density functional theory. For tetragonal and cubic Sr2FeMoO6, band structure and density of states show a slightly different pattern. Both crystal systems are ferrimagnetic and half‐metallic, in agreement with previous theoretical studies by diverse methods. Energy calculation indicates that the tetragonal phase is more stable than its cubic analogue by 43 meV. The energy gap in the up‐spin channel is an indirect one with band gap 0.80 eV in tetragonal and 0.85 eV in cubic. For Sr2CoMoO6, half‐metallic is obtained (with an energy gap 1.30 eV in the un‐spin channel), in agreement with previous theoretical study at LSDA level (half‐metallic), but in contrast to the experiment and theoretical study at LSDA+U level in which insulator was obtained. The overlap bond population of Mo–O bond in both compounds is nearly two times larger than that of Fe(Co)–O bond, indicating that Mo–O bond has stronger bond covalency. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The critical behaviors and the phase diagram of the mixed spin‐1/2 and spin‐2 Ising system on the Bethe lattice
Authors: Albayrak Erhan , Yigit Ali
Published: May 2005

The thermal behaviors of the order‐parameters and the phase diagram for the coordination numbers withq= 3, 4, 5 and 6 for the mixed spin‐1/2 and spin‐2 Blume–Capel Ising ferrimagnetic system (J< 0) for the nearest‐neighbor interactions is studied on the Bethe lattice by using the exact recursion equations. All the functions of interest, the sublattice magnetizations, quadrupolar‐order parameter, free energy etc., are obtained in terms of these recursion relations. The second‐ and first‐order phase transition lines, therefore the existence of the tricritical points are investigated in detail by studying the thermal variations of the sublattice magnetizations and the free energy and it was found that the system presents tricritical points forq≥ 5, which means that the nonexistence of the triciritcal point forq= 4 is in agreement with the result of a Monte Carlo simulation and in disagreement with the result of an effective field theory. It should also be mentioned that the system presents two compensation temperatures forq≥ 4, therefore, the lines of the compensation temperatures are also shown in the phase diagrams. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interpreting Degenerate Solutions in Unfolding by Use of the Vector Model and the Compensatory Distance Model
Authors: Deun K. Van , Groenen P. J. F. , Heiser W. J. , Busing F. M. T. A. , Delbeke L.
Published: May 2005

In this paper, we reconsider the merits of unfolding solutions based on loss functions involving a normalization on the variance per subject. In the literature, solutions based on Stress-2 are often diagnosed to be degenerate in the majority of cases. Here, the focus lies on two frequently occurring types of degeneracies. The first type typically locates some subject points far away from a compact cluster of the other points. In the second type of solution, the object points lie on a circle. In this paper, we argue that these degenerate solutions are well fitting and informative. To reveal the information, we introduce mixtures of plots based on the ideal point model of unfolding, the vector model, and on the signed distance model. In addition to a different representation, we provide a new iterative majorization algorithm to optimize the average squared correlation between the distances in the configuration and the transformed data per individual. It is shown that this approach is equivalent to minimizing Kruskal’s Stress-2.
Knowledge of context sensitive spellings as a component of spelling competence: Evidence from Danish
Authors: JUUL HOLGER
Published: May 2005

Spelling performances in 104 Danish children from Grades 4 to 6 were compared across three levels of orthographic transparency. At the first level all spellings that were plausible at the level of the single phoneme were accepted. At the second level spellings were accepted only if they were plausible when the phonological context was considered (context sensitive spellings). At the third level word-specific spelling accuracy was required. There were 16 word items per level, matched for structure and frequency. Scores for context sensitive spellings were intermediate between scores at the phonemic level and the word-specific level, both for vowel and consonant spellings. Scores for context sensitive vowels and consonants were significantly interrelated even when performances at the phonemic and word-specific levels were controlled. The results demonstrate that Danish spellers beyond the initial phases of literacy development rely on phonological entities larger than the single phoneme. They extend similar findings from English in suggesting that knowledge of context sensitive spellings is a separate component of spelling competence.
The Master of an Evil Name: Hillel Baעal Shem and His Sefer ha-Ḥeshek
Authors: Petrovsky-Shtern Yohanan
Published: May 2005

Back in 1993, as senior librarian at the Vernadsky Library in Kiev, Ukraine, in charge of cataloguing a newly uncovered Judaica collection, I came across an enigmatic manuscript entitled Sefer ha-ḥeshek. It did not match the bulk of the Judaica holdings. Nor did it fit in Abraham Harkavy's collection of medieval manuscripts. It was too Ashkenazic for Abraham Firkovich's Karaite papers, and too early for most of S. Ansky's nineteenth-century folkloric materials. The manuscript had a wooden cover, separate from the text, with a copper monogram Sefer ha-ḥeshek in Hebrew (hereafter—SH). SH's title appears randomly as a running head; the author occasionally refers to the title of the manuscript. Primarily because of its size—411 folios, 23 of them blank, some 760 filled pages altogether—and due to its magical contents, I discarded any attempts to identify the manuscript as a version of the well-known Sefer ha-ḥeshek, a twenty-or-so-page kabbalistic treatise on the names of the archangel Metatron attributed to Isaac Luria. Also, since the manuscript is not a commentary on the book of Isaiah or Proverbs, it could neither be Solomon Duran's nor Solomon ha-Levi's Ḥ eshek shelomoh.
The Artist as a Mother and the Birth of Terrible Beauty in the Post-Holocaust World: Ruth Almog's The Inner Lake
Authors: Brenner Rachel Feldhay
Published: May 2005

In her path-breaking study of Israeli women's fiction, Yael Feldman concludes her analysis of Ruth Almog's Roots of Air (1987) with an insightful observation. In this major work, Feldman claims, Almog trespassed into the male writers' territory and became the first among Israeli woman writers to produce an autobiographical fiction of the “portrait of an artist as a young girl.” Feldman concludes that, once the stage of “therapeutic” self-examination, which encompasses “both the oedipal fixation and the daughter–mother identification,” has been completed, “Almog has now embraced the mother in herself.” Indeed, Feldman identifies the next stage in Almog's artistic evolution in her collection of stories, Artistic Mending (1993), suggesting that now the story of another has become the focus of Almog's artistic concern. In Artistic Mending the writer turns her “motherly” attention to life stories of children, mainly second-generation Holocaust survivors, seeking ways to understand, but also “mend” the damaging effects of the tragic historical legacy.
Robert T. Anderson and Terry Giles. The Keepers: An Introduction to the History and Culture of the Samaritans. Peabody, MA: Hendrickson Publishers, 2002. 300 pp.
Authors: Pummer Reinhard
Published: May 2005

The Keepers is a concise and informative introduction to the history and religion of the Samaritans, that branch of the Israelite–Jewish religion that has endured from antiquity to the present among a tiny minority in Palestine and Israel. The book is written in an engaging style that will appeal to a public that would not read specialized works on the subject. At the same time, the information contained in the work is reliable and the authors are careful in their discussions of unsolved (and often unsolvable) issues. In an epilogue, Anderson and Giles underline that there remains a “host of unanswered questions about the history and culture of the Samaritan community” and that this book is “only a beginning” (p. 145).
Lois C. Dubin. The Port Jews of Habsburg Trieste: Absolutist Politics and Enlightenment Culture. Stanford Studies in Jewish History and Culture. Stanford: Stanford University Press, 1999. ix, 335 pp.
Authors: Berkovitz Jay R.
Published: May 2005

The scope of research devoted to the entrance of European Jews into the modern civic realm has expanded steadily in the last two decades. Historians have turned their attention to communities formerly considered only marginally important because of their small size, their location at the periphery of Europe's most significant political and cultural developments, or their failure to correspond to the models of emancipation and enlightenment derived from the historical experience of French and German Jews. This new direction in Jewish historical writing has generated an ever-increasing body of social–historical data and is marked by a growing emphasis on regional factors, particularly urban–rural differences, and a new appreciation for class and gender as categories of analysis. The result—a more highly nuanced picture of modernization—has firmly discredited the dominant Germanocentric perspective favored by previous generations of historians. Now, thanks to the publication of Lois Dubin's outstanding book, The Port Jews of Habsburg Trieste, our understanding of the forces that shaped modern Jewish society and culture has been advanced appreciably. Dubin has succeeded in producing a balanced reassessment of much of the conventional thinking about periodization, modernization, and the role of Haskalah and Emancipation.
Aaron L. Mackler. Introduction to Jewish and Catholic Bioethics: A Comparative Analysis. Washington, DC: Georgetown University Press, 2003. x, 265 pp.
Authors: Newman Louis E.
Published: May 2005

Comparative analysis, especially in the field of religious studies, is widely recognized as among the most difficult of intellectual tasks. How does one do justice to the complexity of both subjects? How does one set the terms of the comparison in a way that accurately captures both similarities and differences? How does one place those similarities and differences in a broader context so that their significance comes to the fore? And how does one present both halves of the comparison in a way that will be equally accessible to readers presumed to be familiar with only one or the other? These challenges are still more formidable when the subjects being compared are “Jewish bioethics” and “Catholic bioethics,” each of which draws on a long ethical tradition, encompasses a wide range of views, and continues to evolve.
Ruth Katz. “The Lachmann Problem”: An Unsung Chapter in Comparative Musicology. Jerusalem: The Hebrew University Magnes Press, 2003. 415 pp. CD encl.; David M. Schiller. Bloch, Schoenberg & Bernstein: Assimilating Jewish Music. New York: Oxford University Press, 2003. x, 199 pp.; Marsha Bryan Edelman. Discovering Jewish Music. Philadelphia: Jewish Publication Society, 2003. xii, 396 pp. CD encl.
Authors: Cohen Judah M.
Published: May 2005

Jewish music study is a loosely unified field that brings together strands from several scholarly traditions. Researchers trained in historical musicology typically use document study, note analysis, and contemporary aesthetic writings to examine how questions of “Jewishness” manifest themselves in the works of selected composers. Ethnomusicologists frequently utilize ethnographic fieldwork methods developed for studying musical practices of Jewish communities within a broad cultural and symbolic system. Jewish music researchers in Israel commonly focus on comparative cultural projects intended to illuminate stylistic or song-based pathways of transmission from one age or culture to the next. Cultural theorists tend to situate music as a medium for negotiating the borders between Jews and other groups. And with the lay public in mind, specialists and nonspecialists alike have generated numerous popular textbooks claiming to cover “Jewish music.” Each of these disciplines asks different questions about the nature of sound within Jewish contexts; yet central to all is the question of how the sound itself reflects concepts of Jewish life—providing researchers with a richly evocative common ground for substantive and interdisciplinary study.
Assessment of operability for common arterial trunk without cardiac catheterisation
Authors: Hosseinpour Amir-Reza , Shinebourne Elliot A.
Published: May 2005

Pulmonary vascular disease is a risk factor for the surgical management of common arterial trunk. Surgical repair, therefore, is usually performed in early infancy, before irreversible changes can occur in the epulmonary vasculature. Because of this, there has been an increasing tendency to dispense with cardiac catheterisation as a means of assessing pulmonary vascular disease. Cardiac catheterisation, nonetheless, is still performed when there is a risk of pulmonary vascular disease, such as in older children. There are no clear guidelines, however, as to who should be catheterised. We have developed a simple screening test to help make this decision.
Mid-term effects of implanting stents for relief of aortic recoarctation on systemic hypertension, carotid mechanical properties, intimal medial thickness and reflection of the pulse wave
Authors: Agnoletti Gabriella , Bonnet Caroline , Bonnet Damien , Sidi Daniel , Aggoun Yacine
Published: May 2005

Objective:Primary implantation of stents is an accepted technique for treating aortic recoarctation, albeit that the effects of stenting on pressure profiles, carotid mechanical properties, intimal medial thickness, and reflection of the pulse wave have not been systematically investigated.Methods:Over the period from 1 January, 1999, to 31 December, 2002, we implanted stents to relieve aortic recoarctation in 15 patients, with a median age of 17 years, and a range from 7 to 29 years, with a median weight of 56 kilograms, ranging from 20 to 96 kilograms. Indications were a gradient of 20 millimetres of mercury or more measured in all, systemic hypertension at rest in 8, and systemic hypertension at exercise in all. Of the patients, 5 were receiving anti-hypertensive treatment. Before implantation of the stents, and after a mean follow-up of 22 months, all patients underwent an exercise test, vascular echography, and examination of the common carotid artery so as to determine its cross sectional compliance and distensibility, and the augmentation index.Results:The stents were implanted successfully in all patients. The mean gradient was reduced from 27 to 4 millimetres of mercury (p < 0.001). Systolic blood pressure at rest diminished from 140 to 131 millimetres of mercury (p = 0.04), while hypertension at rest regressed in 4 patients. Systolic blood pressure at exercise diminished from 245 to 222 millimetres of mercury (p = 0.018), and hypertension at exercise regressed in 1 patient. Anti-hypertensive treatment is still required for 4 patients. A correlation was found between systolic blood pressure at rest and initial peak-to-peak gradient (r = 0.8), and between initial gradient and percentage reduction of systolic blood pressure at rest at follow-up (r = −0.73). Compliance and distensibility of the common carotid artery were not significantly modified, albeit that the intimal medial thickness diminished from 0.64 to 0.57 millimetres (p = 0.04), and the augmentation index decreased from 5 to −1 (p = 0.012).Conclusions:Primary implantation of stents is effective in mid-term repair of aortic recoarctation. Although there is an improvement in systemic hypertension, the tensional profile and vascular sonography are not normalized. At long term follow-up, the suppression of an early reflection site of the pulse wave could decrease the wall stress of the great elastic vessels, reducing the thickness of the arterial walls.
The potential impact of prophylaxis against bronchiolitis due to the respiratory syncytial virus in children with congenital cardiac malformations
Authors: Rackham Oliver J. , Thorburn Kentigern , Kerr Steve J.
Published: May 2005

Aims:To determine the number of infants in the Mersey and North West regions with congenital cardiac disease for whom palivizumab may be appropriate, and to examine the potential impact of introducing prophylaxis with palivizumab on these patients and their economic management.Methods:We identified those infants deemed to be at high risk, matching the population recently studied by the Cardiac Synagis Group, from the database of the cardiology department of the hospital. The number of patients under the care of the paediatric cardiologists admitted to Alder Hey Hospital with respiratory syncytial viral bronchiolitis over the last three seasons was identified from hospital coding records, and the database of the cardiology department.Results:There are 131 patients at high risk each year. Of these, over the last three “bronchiolitis seasons”, 39 infants have been admitted to the hospital with bronchiolitis due to the respiratory syncytial virus. This represents a hospitalisation rate of 10 per cent, as was seen in the study of the Cardiac Synagis Group. Using a monthly dose of 15 milligrams per kilogram for five doses, the cost per patient is 2,650 pounds sterling for the season. To treat the 131 patients seen at Alder Hey, therefore, would cost 346,800 pounds each year. Applying the reductions in hospitalisation identified in the study by the Cardiac Synagis Group to our population would produce an expected reduction in patients hospitalised from 13 to 7 per year, reducing the total length of stay in our hospital wards from 169 to 76 days, and in the paediatric intensive care unit from 93 to 21 days. This amounts to a potential saving of 190,800 pounds per year. Reducing transfers to more distant paediatric intensive care units for referrals refused because of lack of beds could save an additional 50,000 pounds.Discussion:We estimate the net cost of introducing palivizumab for this population to be 106,000 pounds per year. There would, of course, be additional costs involved in setting up this service, as well as additional savings and benefits. This cost is comparable with other new biologic therapies now routinely used in the United Kingdom, such as etanercept for juvenile arthritis. There are, currently, no other obvious therapies that have the potential to reduce admissions to hospital and intensive care during the winter months, when beds are at their most scarce.
A case of long QT syndrome associated with familial occurrence of persistent patency of the arterial duct
Authors: Murugan Subramanian Jothi , Parsons Jonathan M. , Bennett Chris
Published: May 2005

We describe an occurrence of long QT syndrome in association with persistent patency of the arterial duct in members of a family. Patency of the arterial duct was diagnosed in family members of 4 successive generations. The index case had long QT syndrome associated with such a patent duct. Another patient had long QT syndrome, but associated with a ventricular septal defect. We postulate that there may be a common genetic mechanism for long QT syndrome and persistent patency of the arterial duct.
Rapid progression of long-segment coarctation in a patient with Williams' syndrome
Authors: Arrington Cammon , Tristani-Firouzi Martin , Puchalski Michael
Published: May 2005

Over a period of 6 days, a three-week-old male developed a long-segment coarctation, with sub-total obstruction of the descending aorta, immediately distal to the left subclavian artery. On the 24th day of life, the stenotic region was repaired by placement of a pulmonary allograft patch measuring 3 centimetres in length. Severe diffuse vascular medial thickening was discovered at the operation. Subsequent fluorescence in-situ hybridization proved positive for Williams' syndrome. To our knowledge, this is the first report of rapidly progressive infantile arteriopathy in the setting of Williams' syndrome.
Slow and wide QRS complex tachycardia as a unique complication following radiofrequency catheter ablation of a left-sided accessory pathway in a child
Authors: Vatasescu Radu , Kornyei Laszlo , Szili-Torok Tamas
Published: May 2005

Radiofrequency lesions can, theoretically, be the substrate for new persistent arrhythmias. As far as we know, this has never previously been encountered after transcatheter ablation of accessory pathways. A child with Wolff–Parkinson–White syndrome was referred for radiofrequency catheter ablation of a left-sided accessory pathway. After successful ablation of the accessory pathway using a retrograde transaortic approach, the child developed an incessant wide QRS complex tachycardia at slow rate that was resistant to pharmacologic interventions. The focus of the tachycardia was identical to the ventricular site of insertion of the eliminated accessory pathway.
Muslim Narratives of Schooling, Social Mobility and Cultural Difference: A Case Study in Multi-ethnic Northwest China
Authors: YI LIN
Published: May 2005

This paper draws upon fieldwork among a Muslim community in the Qinghai-Gansu borderland areas to explore how the desire of Muslims to achieve social mobility through education is blocked by the larger society which regards them as ‘familiar strangers’. This can be understood as a tension between their desire for full social citizenship in the form of rights to employment and education and the limited social and cultural capital they possess that prevents them from achieving the former. This tension is primarily caused by the party-state's ambivalence over the project of state nation building and minority rights. By focusing on Muslim narratives of their experiences in the cultural exclusion, this case study attempts to scrutinize how the cultural exclusion affects the engagement of ethnic minorities in education as well as the larger society, although it has been recognized that the experience of exclusion varies between minority groups.
Low‐latitude auroras observed in Japan: 1999–2004
Authors: Shiokawa K. , Ogawa T. , Kamide Y.
Published: May 2005

From routine observations by means of highly sensitive all‐sky cameras and tilting‐filter photometers, a total of 20 low‐latitude aurora events in Japan were identified during the high solar activity period of 1999–2004. This indicates that the invisible‐level auroras appear rather frequently in the northern sky of Japan during magnetic storms. These auroras are characterized by an enhancement in red (630.0 nm) emissions in the northern sky during magnetic storms, probably at geomagnetic latitudes higher than ∼40–50°. We show examples of stable auroral red (SAR) arcs, which are typically observed during the recovery phase of storms. We also found several red aurora events that occurred at the initial phase of magnetic storms. Intensifications as well as equatorward motion of the auroras were observed in association with storm time substorms. Green line emissions (557.7 nm) were often enhanced (∼1 kR) not only in the northern sky but also in the whole sky. Some auroras show weak enhancements (∼10 R) of N2+1N (427.8 nm) in the northern sky in the morning hours. We discuss possible causes of these emissions in light of magnetospheric disturbances and thermospheric dynamics.
Testing the stress shadow hypothesis
Authors: Felzer Karen R. , Brodsky Emily E.
Published: May 2005

A fundamental question in earthquake physics is whether aftershocks are predominantly triggered by static stress changes (permanent stress changes associated with fault displacement) or dynamic stresses (temporary stress changes associated with earthquake shaking). Both classes of models provide plausible explanations for earthquake triggering of aftershocks, but only the static stress model predicts stress shadows, or regions in which activity is decreased by a nearby earthquake. To test for whether a main shock has produced a stress shadow, we calculate time ratios, defined as the ratio of the time between the main shock and the first earthquake to follow it and the time between the last earthquake to precede the main shock and the first earthquake to follow it. A single value of the time ratio is calculated for each 10 × 10 km bin within 1.5 fault lengths of the main shock epicenter. Large values of the time ratio indicate a long wait for the first earthquake to follow the main shock and thus a potential stress shadow, whereas small values indicate the presence of aftershocks. Simulations indicate that the time ratio test should have sufficient sensitivity to detect stress shadows if they are produced in accordance with the rate and state friction model. We evaluate the 1989 MW 7.0 Loma Prieta, 1992 MW 7.3 Landers, 1994 MW 6.7 Northridge, and 1999 MW 7.1 Hector Mine main shocks. For each main shock, there is a pronounced concentration of small time ratios, indicating the presence of aftershocks, but the number of large time ratios is less than at other times in the catalog. This suggests that stress shadows are not present. By comparing our results to simulations we estimate that we can be at least 98% confident that the Loma Prieta and Landers main shocks did not produce stress shadows and 91% and 84% confident that stress shadows were not generated by the Hector Mine and Northridge main shocks, respectively. We also investigate the long hypothesized existence of a stress shadow following the 1906 San Francisco Bay area earthquake. We find that while Bay Area catalog seismicity rates are lower in the first half of the twentieth century than in the last half of the nineteenth, this seismicity contrast is also true outside of the Bay Area, in regions not expected to contain a stress shadow. This suggests that the rate change is due to a more system wide effect, such as errors in the historical catalog or the decay of aftershocks of the larger 1857 Fort Tejon earthquake.
Tunnel magnetoresistance of disordered, low-moment Co2MnSi Heusler alloy thin films
Authors: Nakajima K. , Fen G. , Caillol C. , Dorneles L. S. , Venkatesan M. , Coey J. M. D.
Published: May 2005

Thin films of Co(1−x−y)MnxSiy (x=0.18–0.26 and y=0.23–0.29) were deposited from elemental targets onto thermal-oxidized Si substrates at room temperature using dc magnetron cosputtering. The as-deposited films appear to be amorphous showing no distinguishable peaks in x-ray diffraction, and the magnetic moment at room temperature is nearly zero. Despite of its low magnetic moment (less than 0.001μB per formula), the disordered Heusler magnetic tunnel junctions show tunnel magnetoresistance ratios as large as 10% at room temperature. The dependence of the tunnel magnetoresistance ratio on compositions x and y is also reported.
Spin polarization measurements on polycrystalline strontium ruthenates using point-contact Andreev reflection
Authors: Sanders J. , Woods G. T. , Poddar P. , Srikanth H. , Dabrowski B. , Kolesnik S.
Published: May 2005

Point-contact Andreev reflection (PCAR) measurements were made on bulk polycrystalline SrRu0.8Ti0.2O3 and SrRu0.92O3 samples to determine the transport spin polarization. The parent compound SrRuO3 undergoes ferromagnetic ordering at TC∼160K with relatively high spin polarization (∼60%). For the SrRu0.8Ti0.2O3 and SrRu0.92O3 samples, a reduction in TC occurs. Moreover, our measurements indicate that the SrRu0.8Ti0.2O3 system retains a high degree of spin polarization (P∼0.6), similar to the parent compound. However, due to the insulating nature of SrRu0.92O3, the PCAR technique did not yield information on P. Instead, the data displayed nonlinear I–V consistent with the tunnelinglike spectra.
Current driven domain wall motion in magnetic U-pattern
Authors: Tsai J. L. , Lee S. F. , Liou Y. , Yao Y. D. , Chen T. Y. , Cheng K. W.
Published: May 2005

We have studied the current induced domain wall motion by using patterned U geometry. The observation of two magnetic states of the U-pattern was evidenced. One is the vortex domain wall at the center of semicircular arc in U-pattern and the other is the continuous magnetic state without wall. We investigated the influence of the positive and negative dc current injection on domain wall motion before switching field with density on the order of ∼107A∕cm2. The critical current varied dramatically as the bias field is close to the switching field and only gradually as the field is far away from the switching field.
Current induced magnetic switching in Ni80Fe20, Ni, Fe, and Co wires
Authors: Lepadatu S. , Xu Y. B. , Ahmad E.
Published: May 2005

The current induced switching mechanism and domain wall magnetoresistance are studied in ferromagnetic wires of Ni80Fe20, Ni, Fe, and Co patterned with a nanocontact. A discontinuous resistance change is observed in the current–voltage measurements of Ni80Fe20 and Ni, 0.13% and 0.124%, respectively, at a critical current of ∼107A∕cm2. The magnetoresistance measurements of the Ni80Fe20 and Ni samples have shown a magnetoresistance enhancement within ±20Oe of the zero point when measured at a current below the critical current and of the same percentage change as for the current–voltage measurements. For the Fe and Co samples no resistance change which could be attributed to domain wall scattering was found. The differences in the current induced switching mechanism and domain wall magnetoresistance of the different materials studied are contrasted and analyzed.
Oxidation of tunnel barrier metals in magnetic tunnel junctions
Authors: Yang J. Joshua , Ladwig Peter F. , Yang Ying , Ji Chengxiang , Chang Y. Austin , Liu Feng X. , Pant Bharat B. , Schultz Allan E.
Published: May 2005

The oxidation of an ultrathin metal layer (<1nm) to form an oxide tunnel barrier is of critical importance for the fabrication of magnetic tunnel junctions (MTJs) with low product of resistance and area (R×A). Nonuniform and excessive or insufficient oxidation will occur by using conventional plasma, air, or O2 and noble gas mixtures as oxidation methods. An oxidation method was investigated to oxidize only an ultrathin layer of metal (such as Y) without oxidizing adjacent ferromagnetic thin film layers. We have now demonstrated that a gas mixture of H2O∕H2 with a fixed chemical potential of oxygen determined by the relative amounts of the two gases can oxidize Y and Ta thin layers while simultaneously keeping a Co ferromagnetic layer completely unoxidized. This universal method can be used to preferentially oxidize a host of other metals with high tendency to form oxides, such as Zr, Hf, Nb, rare earth metals, etc. and may allow us to access the feasible lower limit of barrier thickness in MTJs.
Switching characteristics of submicrometer magnetic tunnel junction devices with perpendicular anisotropy
Authors: Yoo Ilsang , Kim Deok-kee , Kim Young Keun
Published: May 2005

As the pattern size of magnetic tunnel junctions (MTJs) becomes smaller, the vortex of magnetization and fluctuations of switching fields caused by the shape MTJ cells will cause serious writing problems. However, a MTJ structure with perpendicular anisotropy (pMTJ) has shown low saturation magnetization and shape independence during the writing process. In this study, we considered Co∕Pd multilayers that allow better tailor-design of magnetization and anisotropy. A series of calculations based on the Landau–Lifschitz–Gilbert equation were carried out on pMTJs to investigate the effect of size variations and material properties on their transfer behaviors. In a same submicrometer cell size, pMTJ shows better properties for high-density magnetoresistive random access memory (MRAM) against synthetic antiferromagnet MTJs. As the number of bilayer Co∕Pd,n, becomes larger, the coercivity and squareness were enhanced because of shape anisotropy and large effective Ku. Even with a small field, 10 Oe, along the hard axis, the drastic decrease, nearly about 80% of switching field, occurs. As a micromagnetic result, a pMTJ with a cell size of 200 nm and n=3 shows an abrupt increase in coercivity and better squareness.
Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al–N barrier
Authors: Yoshimura S. , Nozawa T. , Shoyama T. , Tsunoda M. , Takahashi M.
Published: May 2005

In order to form ultrathin insulating layer in magnetic tunnel junctions (MTJs), two surface flatting processes of metal films are investigated. Oxygen-additive sputter-deposition process was applied to the bottom Cu electrode and the Al layer to be nitrided. Dry-etching process was applied for the surface treatment of lower Co–Fe layer. As a result, the surface roughness of stacked ultrathin Al layer to be nitrided is reduced from 3.2Å to 1.7Å, and the tunnel magnetoresistance (TMR) ratio of the MTJs increases from 1% to 26% while maintaining resistance-area product (R×A) less than 5×102Ωμm2 in the Co–Fe∕Al(6A)–N∕Co–Fe MTJs. We conclude that the decrease of the surface roughness of Al layer is one of the key factors to realize high performance MTJs with low R×A and high TMR ratio.
Evidence of elastic tunneling in planar YBa2Cu3O7−δ∕La1∕3Ca2∕3MnO3∕La2∕3Ca1∕3MnO3 junctions
Authors: Baca E. , Saldarriaga W. , Prieto P. , Morán O. , Hott R. , Grube K. , Fuchs D. , Schneider R.
Published: May 2005

Evidence of elastic tunneling has been observed in YBa2Cu3O7−δ(S)∕La1∕3Ca2∕3MnO3(AF)∕La2∕3Ca1∕3MnO3(F) junctions. S/AF/F trilayers with thicknesses of ∼100, ∼7, and ∼80nm, respectively, were grown on SrTiO3 (001) substrates. Electrical measurements of the junctions at low temperatures under zero magnetic field display an asymmetry of the I-V and G(V)≡dI∕dV characteristics: for positive voltages, we observed a sharp peak at ∼20meV at 15K; for negative voltages we find at this temperature a peak around −15meV in agreement with the value expected for YBa2Cu3O7−δ. The low values of the conductance G for voltages above the energy gap are discussed.
Mn diffusion and the thermal stability of tunneling spin polarization
Authors: Paluskar P. V. , Kant C. H. , Kohlhepp J. T. , Filip A. T. , Swagten H. J. M. , Koopmans B. , de Jonge W. J. M.
Published: May 2005

We examine the role of Mn diffusion in the thermal stability of tunneling spin polarization P by directly measuring P of Al∕AlOx∕Co∕FeMn and Al∕AlOx∕Co90Fe10∕FeMn junctions using superconducting tunneling spectroscopy (STS). We confirm Mn diffusion in our junctions using x-ray photoelectron spectroscopy after an ultrahigh vacuum 500°C anneal. Surprisingly, and in contrast to the current belief, no drop in P is observed using STS. Therefore, though Mn diffuses significantly, it cannot be solely responsible for the drop in tunneling magnetoresistance observed after postdeposition anneals above 300°C.
High-pressure vibrational spectroscopy of sulfur dioxide
Authors: Song Yang , Liu Zhenxian , Mao Ho-kwang , Hemley Russell J. , Herschbach Dudley R.
Published: May 2005

Solid sulfur dioxide was investigated by vibrational spectroscopy over a broad pressure and temperature range, extending to 32.5GPa at 75–300K in diamond anvil cells. Synchrotron infrared spectra provided the first measurements of the pressure dependence of the lattice modes in the far-IR region. Below 17.5GPa, two fundamentals exhibit splittings enhanced by pressure. The asymmetric stretching mode of SO2 exhibits a remarkable pressure-induced softening. The observations are consistent with the ambient pressure Raman measurements indicating that SO2 crystallizes in an acentric cell, but are inconsistent with a previously proposed interpretation that the structure of the high-pressure phase consists of (SO2)3 clusters. Dramatic changes in the Raman spectra are found above 17.5GPa at room temperature. These indicate major changes in structure and possible formation of SO2 clustering with an enlarged unit cell. The behavior at low temperature differs from that at room temperature. These findings provide constraints on the phase diagram of sulfur dioxide.
Density-functional theory and Monte Carlo simulation for the surface structure and correlation functions of freely jointed Lennard-Jones polymeric fluids
Authors: Li Zhidong , Cao Dapeng , Wu Jianzhong
Published: May 2005

We present a nonlocal density-functional theory of polymeric fluids consisting of freely jointed Lennard-Jones chains with explicit consideration of the segment size, van der Waals attraction, and structural correlations due to chain connectivity. The excess Helmholtz energy functional is derived from a modified fundamental measure theory for the short-ranged repulsion and the first-order thermodynamic perturbation theory for chain connectivity. The contribution of the long-ranged attraction to the Helmholtz energy functional is taken into account using a quadratic density expansion with the direct correlation function obtained from the first-order mean-spherical approximation. The numerical performance of the density-functional theory is compared well with the simulation results from this work as well as those from the literature for the segment-level density profiles and correlation functions of Lennard-Jones chains in slit pores, near isolated nanoparticles, or in bulk.
A mathematical model of crystallization in an emulsion
Authors: Feltham Daniel L. , Garside John
Published: May 2005

A mathematical model incorporating many of the important processes at work in the crystallization of emulsions is presented. The model describes nucleation within the discontinuous domain of an emulsion, precipitation in the continuous domain, transport of monomers between the two domains, and formation and subsequent growth of crystals in both domains. The model is formulated as an autonomous system of nonlinear, coupled ordinary differential equations. The description of nucleation and precipitation is based upon the Becker–Döring equations of classical nucleation theory. A particular feature of the model is that the number of particles of all species present is explicitly conserved; this differs from work that employs Arrhenius descriptions of nucleation rate. Since the model includes many physical effects, it is analyzed in stages so that the role of each process may be understood. When precipitation occurs in the continuous domain, the concentration of monomers falls below the equilibrium concentration at the surface of the drops of the discontinuous domain. This leads to a transport of monomers from the drops into the continuous domain that are then incorporated into crystals and nuclei. Since the formation of crystals is irreversible and their subsequent growth inevitable, crystals forming in the continuous domain effectively act as a sink for monomers “sucking” monomers from the drops. In this case, numerical calculations are presented which are consistent with experimental observations. In the case in which critical crystal formation does not occur, the stationary solution is found and a linear stability analysis is performed. Bifurcation diagrams describing the loci of stationary solutions, which may be multiple, are numerically calculated.
Hydrogen bonding in supercritical tert-butanol assessed by vibrational spectroscopies and molecular-dynamics simulations
Authors: Andanson J-M. , Soetens J-C. , Tassaing T. , Besnard M.
Published: May 2005

We have investigated the state of aggregation in supercritical tert-butanol (T=523K,0.05<ρ<0.4gcm−3) by means of vibrational spectroscopies (infrared and Raman) and molecular-dynamics (MD) simulations. A quantitative band shape analysis of the spectra associated with the OH stretching mode of tert-butanol has been done using activities computed by ab initio calculations on small clusters. This allows us to determine the degree of hydrogen bonding and populations of oligomers. These latter quantities have been derived from MD simulations and very consistent results are found with experiments. These results show that hydrogen bond still exist in supercritical tert-butanol and that the fluid mainly consists of oligomers smaller than tetramers.
Tetrahedral order in homologous disaccharide-water mixtures
Authors: Branca C. , Maccarrone S. , Magazù S. , Maisano G. , Bennington S. M. , Taylor J.
Published: May 2005

The present work aims at evidencing the “kosmotrope” nature of trehalose through the analysis of inelastic neutron scattering measurements on trehalose and sucrose water solutions at different temperatures. Neutron spectra were collected by using the spectrometer MARI at the ISIS pulsed neutron source of the Rutherford Appleton Laboratory (Chilton, UK). To study the structural modifications induced on the tetrahedral hydrogen-bond network of water by homologous disaccharides, as a first step, the vibrational properties of pure water at different temperatures have been investigated. In particular, the temperature behavior of the intramolecular OH stretching mode has been analyzed. Successively, the vibrational properties for pure water have been compared with those of the sugar water solutions focusing the attention on the tetrahedral network-forming tendency. Finally, the obtained findings have been compared with previous Raman scattering evidences, and the results interpreted in the frame of recent molecular dynamics simulation works.
Separated carrier injection control in carbon nanotube field-effect transistors
Authors: Pourfath M. , Gehring A. , Ungersboeck E. , Kosina H. , Selberherr S. , Cheong B. H. , Park W. J.
Published: May 2005

The ambipolar behavior limits the performance of carbon nanotube field-effect transistors. A double-gate device is proposed to suppress this behavior. In this device, the first gate controls carrier injection at the source contact and the second one controls carrier injection at the drain contact, which can be used to suppress parasitic carrier injection. The effect of the second gate voltage on the performance of the device has been investigated. Our results indicate that by applying a proper voltage range to the second gate, improved device characteristics can be achieved.
Paradoxes related to electron-hole scattering in junction structures
Authors: Mnatsakanov T. T. , Levinshtein M. E. , Tandoev A. G. , Yurkov S. N. , Palmour J. W.
Published: May 2005

Electron-hole scattering (EHS) affects the operation of all bipolar semiconductor devices at a high current density. From a physical point of view, EHS has always been considered an additional “frictional mechanism” for free carriers. Because any friction is a dissipative process, the main conclusion of numerous studies devoted to EHS is that the EHS increases the forward voltage drop across semiconductor devices. As a consequence, the inclusion of EHS inevitably raises the energy loss in bipolar devices. It is shown in this paper that EHS leads to a decrease in the forward voltage drop across bipolar devices in some important cases. This decrease may be substantial from a practical point of view.
Memory effect in [001] poled 0.92Pb(Zn1∕3Nb2∕3)O3–0.08PbTiO3 single crystals
Authors: Shen Mingrong , Cao Wenwu
Published: May 2005

We have conducted dielectric and pyroelectric measurements in [001] poled rhombohedral phase 0.92Pb(Zn1∕3Nb2∕3)O3–0.08PbTiO3 single crystals from room temperature to 250 °C. An interesting poling history dependence has been revealed from the experimental results. Compared with room-temperature poled samples, crystals poled via the field-cooling method have a much lower rhombohedral-to-tetragonal phase transition temperature and have enhanced spontaneous polarization while heating up to the tetragonal phase. Such phenomena may be explained by the memory effect of dipolar defect alignment in the sample poled by the field-cooling method.
Optoelectronic characteristics of single CdS nanobelts
Authors: Li Q. H. , Gao T. , Wang T. H.
Published: May 2005

Optoelectronic properties of single CdS nanobelts are investigated by performing transport measurements with different laser ON/OFF circles. The current increases linearly with the bias voltage in the dark, and superlinearly under illumination. The superlinear increase can be related to the enhanced mobility due to the partial release of surface adsorbates under illumination. The current jumps up by five orders of magnitude upon turning on the laser with an intensity of 0.3W∕cm2 within 91ms and decreases by five orders 6ms just after turning off the laser. The high sensitivity and fast response in the visible range indicate potential applications of CdS nanobelts in realizing optoelectronic switches.
Possible method for diagnosing waves in dusty plasmas with magnetized charged dust particulates
Authors: Rosenberg M. , Shukla P. K.
Published: May 2005

We discuss theoretically a possible method for diagnosing some features of dust wave behavior in a magnetized plasma containing small (tens of nm) charged dust grains whose motion is magnetized. It is easier to magnetize a small dust particle because its charge-to-mass ratio increases as its size decreases. However, it is more difficult to use the backscattering of light from the dust as a diagnostic as the dust size decreases below the diffraction limit. The idea proposed here is to measure the reduction in transmitted UV or optical light intensity due to enhanced extinction by small metal dust particles that have surface plasmon resonances at those wavelengths. Such measurements could indicate the spatial location of the dust density compressions or rarefactions, which may yield information on the dust wave behavior, or perhaps even charged dust transport. Parameters that may be relevant to possible laboratory dusty plasma experiments are discussed.
Time-difference between the electric field components of signals prior to major earthquakes
Authors: Varotsos P. A. , Sarlis N. V. , Skordas E. S.
Published: May 2005

We present data demonstrating that the electric field components of low-frequency (⩽1Hz) precursory electric signals exhibit markedly different time evolutions. This difference, if properly measured, upon considering that the electromagnetic fields obey diffusion-type equations, is of profound importance since it can reveal the distance of the measuring site from the epicenter of the impending earthquake.