bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the magnetization behavior in Nd and Sm substituted La0.7Pb0.3MnO3 systems
Authors: Shen C. Y. , Kao M. C. , Chen H. Z. , Young S. L. , Shi J. B. , Lin C. C. , Lin C. H. , Ou C. R. , Jhang M. C. 
Published: December 2007

AbstractIn this work, the magnetization behavior of two maganite oxide systems, La0.7–xNdxPb0.3MnO3 and La0.7–xSmxPb0.3MnO3, has been synthesized. The partial replacement of La ions by Nd or Sm results in a considerable decrease in the ferromagnetic ordering temperature TC. Moreover, clearly irreversible behavior in the field‐cooling and zero‐field‐cooling curves at a low applied field shows the short‐range spin order phase. These facts are in agreement with the smaller ionic radii of Nd (0.127 nm) and Sm (0.124 nm) ions in contrast to La ion (0.136 nm) with the corresponding larger distortion of perovskite structure. The saturation magnetization MS is increased as Nd content is increased which provides a relative contrast with the decrease of MS by the increase of Sm content. This can be interpreted in terms of the competition between the suppression of ferromagnetism due to structure tuning induced by the small ionic radius of the interpolated cation into the La‐site and the increase of ferromagnetic spins due to the introduction of magnetic Nd or Sm ions with f ‐shell electrons. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic and recording performance of perpendicular magnetic media with new soft underlayer structure
Authors: Yoon S. Y. , Kong S. H. , Lee H. S. , Lim C. K. , Kim H. J. , Oh H. S. , Park J. B. , Choa S. H. 
Published: December 2007

AbstractIn this study, we introduced the new concept SUL (Soft Underlayer) of PMR (Perpendicular Magnetic Recording) media for the superior recording performance. The recording performance of PMR media with various SUL types were investigated by Guzik spin stand. Our new concept SUL, which was denoted by the modified SAF (Synthetic Antiferromagnetic Coupling) structure, showed more excellent recording properties than those of others. These improved recording performances may be generated by decreased SUL noise and increased filed gradient with new SUL structure. The obtained results indicated that the modified SAF SUL structure can be helpful to high recording density. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New method for detecting the early stage of structural changes by using HTSC squid‐based magnetometer
Authors: Park D. G. , Chandrasekhar A. , Kim D. W. , Timofeev V. P. , Cheong Y. M. 
Published: December 2007

AbstractThe new method of detection the early stage of structural changes in stainless steel samples is proposed and used. It includes the registration of initial magnetization line shift, the zero region of magnetic hysteretic loop (B‐H). This method is based on the use of high sensitive SQUID magnetic sensor. As a result, the spontaneous magnetic moment that treated sample manifests in zero external magnetic fields is recoded. The magnetic moments of cold worked 316 stainless steel have been measured as an application of this type of HTSC (High Tempe rapture SuperConducting) SQUID‐based magnetometer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design optimization of the bit and word lines in magnetic random access memory in the Stoner‐Wohlfarth model
Authors: Lee T. H. , Lim S. H. 
Published: December 2007

AbstractThe optimization in the design of the bit and word lines in magnetic random access memory is performed in the Stoner‐Wohlfarth model. This is done by calculating the asteroid curves as a function of the angle between the bit and word lines. The calculation essentially involves finding the energy minima of the system. The switching field is reduced greatly when the angle between the bit and word lines is deviated from the right angles. Thermal stability of half‐selected cells, which is estimated by calculating the energy barrier, is also improved significantly. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier doping dependence of the Tc in double perovskite Sr2FeMoO6
Authors: Kim J. , Kim C. S. , Lee B. W. 
Published: December 2007

AbstractCarrier doping effects on the Curie temperature Tc of double perovskite Sr2FeMoO6 have been studied along the series polycrystalline Sr2–xAxFeMoO6 (A = Ba and K) samples. The partial substitution of K+ for Sr2+ considerably reduces the Tc from 399 K for x = 0 to 352 K for x = 0.2 with cell volume increasing. This decrease of Tc with K+ doping originates from carrier doping effects in addition to ionic size ones. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The changes of the magnetic properties in ion irradiated Fe–Cr alloys
Authors: Park D. G. , Heo K. C. , Kim W. W. , Choong Y. M. 
Published: December 2007

AbstractFe–Cr alloys are one of the important structural materials for fusion reactor applications, and often used as a model alloys for studying the basic mechanisms governing their behavior under an irradiation. In this study, Fe ions are irradiated on to Fe–Cr alloys with 9% of Cr contents. The magnetic Barkhausen Noise (BN) and Ferro Magnetic Resonance (FMR) experiments are conducted to investigate the changes of their magnetic properties under an ion irradiation. The BN and FMR resonance fields are increased with an increasing ion dosage. The directional ordering by irradiation induced defects seems to be responsible for the changes in the magnetic properties. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Permanent magnets circuit for collagen orientation
Authors: Shinohara Tadashi , Saito Tomoyuki , Saito Daisuke , Kotani Makoto , Aoki Masaaki 
Published: December 2007

AbstractTo synthesize artificial bones, the collagen orientation is one of the key issues. It is reported that high magnetic field could be generated by superconducting magnets, are effective in controlling collagen orientation. In this paper, magnetic circuit using permanent magnets for collagen orientation is studied. As the results, a compact magnetic circuit with magnetic field strength around 3 T has been developed. By using the magnetic circuit, collagen was highly oriented, and orientation order was 0.9. Mouse osteoblast cells were seeded on the orientated collagen solution and cultured. The collagen‐gel shrinkages by cells were observed. The shrinkage rates of oriented collagen are higher than that of not oriented one. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of ion‐beam bombardment and post‐annealing on the structural and magnetic properties of Fe/Pt multilayers
Authors: Guo J.‐Y. , Liu C.‐Y. , Ouyang H. , Lin K.‐W. , Tsai C.‐J. , Lierop J. van , Phuoc N. N. , Suzuki T. 
Published: December 2007

AbstractWe have investigated the structures and magnetic properties of as‐deposited and annealed [Pt(20 Å)/Fe(15 Å)]10/Pt(30 nm) multilayers under different End‐Hall voltages (VEH = 0 ∼ 150 V). The films deposited with no End‐Hall voltage consisted of Fe (a = 2.91 Å), Pt (3.96 Å), and disordered FePt (a = 3.82 Å) phases. Increasing VEH helps compact the individual Fe and Pt layers, while preventing FePt intermixing. However, increasing the annealing temperature to 550 °C resulted in an ordered f.c.t. FePt (a = 3.85 Å, c = 3.73 Å) phase for films deposited with VEH = 0V, and a mixture of Fe and Pt phases with grain coarsening was found for films prepared with VEH = 150 V. A drastic increase in coercivity (Hc ∼ 4600 Oe) in the annealed sample (VEH = 0 V) is attributed to the formation of FePt phases. A decrease in Hc with increasing VEH indicates that FePt formation may be suppressed via more energetic ion beam bombardment that resulted in the activation barrier of diffusion increasing dramatically. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and magnetic properties of ion‐beam bombarded Co/Pt multilayers
Authors: Lin K.‐W. , Guo J.‐Y. , Lin S.‐R. , Ouyang H. , Tsai C.‐J. , van Lierop J. , Phuoc N. N. , Suzuki T. 
Published: December 2007

AbstractA series of [Pt(2 nm)/Co(2 nm)]10/Pt(30 nm) multilayers were deposited by using an ion‐beam technique. X‐ray diffraction and transmission electron microscopy results have shown that as‐deposited samples consist of h.c.p. Co and f.c.c. Pt phases. Disordered CoPt3 phases were developed with increasing End‐Hall voltage (VEH) that induces greater ion‐beam bombardment energy during deposition. This indicates that intermixing of Co and Pt increases with ion‐beam bombardment. The coercivities (ranging from 100 Oe to 300 Oe) of Co/Pt multilayers decreased with increasing VEH. After annealing, the formation of CoPt3 was observed in these ion‐beam bombarded samples, resulting in lower coercivities (Hc ∼ 50 Oe). The depressed transition temperature of CoPt3 for films deposited with the largest VEH was attributed to distorted CoPt3 structures that appeared with annealing. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐transport properties of ZnO/La0.7Sr0.3MnO3 bilayer on p‐Si(100)
Authors: Park S. Y. , Lee Hyung Woo , Lee Young Soo , Wang D. F. , Lee Y. P. , Rhee J. Y. 
Published: December 2007

AbstractPolycrystalline ZnO/La0.7Sr0.3MnO3 (LSMO) heterostructures were fabricated onto Si(100) substrates by magnetron sputtering. A rectifying behavior, as well as an enhanced magnetoresistance (MR) ratio (∼ 12%), was obtained in the heterostructure with respect to the LSMO single layer (a MR ratio ∼ 6%). The degradation of the rectifying behavior for the LSMO layer thinner than 20 nm is mainly due to the change in hole concentration. We suggest a possibility that the magneto‐transport and the magneto‐optical properties of manganites can be modified by the formation of this kind of heterostructure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Percolated perpendicular medium of FePt‐MgO/MgO bilayer films for ultra‐high magnetic recording
Authors: Sun An‐Cheng , Tsai Y. C. , Hsu Jen‐Hwa , Kuo P. C. , Huang H. L. , Sharma Puneet 
Published: December 2007

AbstractPercolated perpendicular (FePt)100–x‐(MgO)x thin films with x = 0–10.07 vol.% were fabricated on glass substrate with MgO(200)underlayer. When the substrate temperature was 580 oC, a significant enhancement in coercivity was observed at 1.23 vol.% of MgO, which was due to the precipitation of MgO in FePt film causing the hindrance in domain wall motion. As the amount of MgO was increased above 1.23 vol.%, the percolated perpendicular structure began to transform into granular perpendicular structure. Meanwhile, the MgO was found to segregate along grain boundaries of FePt grains, leading to the reduction of FePt grain size. As a result the coercivity and ordering parameter became smaller. In this study the percolated perpendicular medium using FePt film with doping adequate amount of MgO has shown possibility to be an efficient method to increase recording density if the film processing conditions are optimized further. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of film thickness on the soft magnetic properties of sputtered Co‐Fe‐Hf‐O films
Authors: Le Anh‐Tuan , Ha Nguyen Duy , Phan Manh‐Huong , Lee Kwang‐Eun , Kim Chong‐Oh , Lee Heebok , Yu Seong‐Cho 
Published: December 2007

AbstractInfluence of film thickness on the soft magnetic properties of Co19.35Fe53.28Hf7.92O19.35 films, which were deposited on Si(100) substrates using the oxygen reactive RF‐sputtering method, has been thoroughly investigated. It is found that as the film thickness (t) increases from 50 to 430 nm, the easy‐axis coercivity (HCE) strongly decreases from 26.2 to 1.5 Oe, while the hard‐axis anisotropy field (HKH) significantly increases from 68.7 to 84.8 Oe and the saturation magnetization (4πMs) tends to increase from 16.8 to 19.7 kG. As t exceeds 430 nm, HKH gradually decreases, while both HCE and 4πMs remain almost unchanged. It reveals that a strong phase separation appears to occur in films with t > 430 nm, resulting in the decrease of HKH. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Giant parallel and perpendicular exchange biases in MnPd/Co bilayers
Authors: Nam Nguyen Thanh , Thuy Nguyen Phu , Tuan Nguyen Anh , Phuoc Nguyen Nguyen , Suzuki Takao 
Published: December 2007

AbstractA systematic study of exchange bias in MnPd/Co bilayers has been carried out in both parallel and perpendicular directions, where the dependences of blocking temperature, exchange bias and unidirectional anisotropy constant on the thicknesses of MnPd and Co layers were investigated. One of the particular interests is that the blocking temperature of parallel exchange bias is higher than that of perpendicular exchange bias which can be interpreted as the difference of the ordering in parallel and perpendicular direction. The other is that a huge unidirectional anisotropy constant, JK = 5.5 erg/cm2 was observed, which is in reasonable agreement with the theoretical prediction based on the model by Meiklejohn and Bean. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical breakdown of Co/AlOx/Co tunneling junction
Authors: Horikiri K. , Shiiki K. 
Published: December 2007

Abstract To clarify a mechanism of electrical breakdown of magnetic tunneling junctions (MTJs), the change of characteristics by constant voltage stress was investigated. There were two breakdown processes. In the case of low applied voltage stress, tunnel resistance increased. On the other hand, if the applied voltage stress was higher, tunnel resistance decreased monotonously. The lifetime of MTJs with an inhomogeneous barrier was shorter than that of MTJs with a homogeneous barrier. In the breakdown process, the homogeneous barrier gradually became inhomogeneous, just before the breakdown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Mössbauer study of a Ge–Fe thin film
Authors: Ahn G. Y. , Kim C. S. , Lim S. H. 
Published: December 2007

AbstractMagnetic phases of a Ge48.2Fe51.8 (in atomic%) thin film, fabricated by thermal co‐evaporation onto an oxidized Si substrate, are analyzed by Mössbauer spectroscopy as well as magnetometry. Magnetic measurements indicate a superparamagnetic behavior due to the formation of Fe precipitates in an amorphous matrix with an average blocking temperature of 160 K and a spin glass behavior with a spin freezing temperature of 30 K. The superparamagnetic behavior is confirmed from the Mössbauer spectra taken at room temperature. The isomer‐shift values indicate that the Fe atom in the amorphous phase is in the high‐spin Fe3+ charge state. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Can undoped semiconducting oxides be ferromagnetic?
Authors: Hong Nguyen Hoa , Barla Alessandro , Sakai Joe , Huong Nguyen Que 
Published: December 2007

AbstractExperimental results on TiO2, HfO2, In2O3, and ZnO have confirmed that ferromagnetism (FM) is certainly possible in undoped oxide thin films. As for the TiO2, In2O3, and HfO2 films, FM is most probably due to oxygen vacancies. Additionally, our X‐ray magnetic circular dichroism (XMCD) measurements on TiO2 films doped with transition ‐ metal elements (Cr, Mn, Co) show that these contribute only with a paramagnetic component to the total magnetization, thus implying that FM in these films must originate from the TiO2 host matrix. As for ZnO, our data have revealed that the FM in this compound does not originate from oxygen vacancies but more likely from defects on Zn sites. We propose a model that is based on an electronic structure calculation using the tight binding method in the confinement configuration: vacancy site in TiO2, HfO2, In2O3 films could create spin splitting and high spin state, so that the exchange interaction between the electrons surrounding the oxygen vacancy with the local field of symmetry could lead to a FM ground state of the systems. The theoretical calculations give the results of 3.18 μB per vacancy for TiO2, 3.05 μB /vac for HfO2 and 0.16 μB /vac for In2O3. It also proves that the mechanism for ZnO system must be different, that FM cannot stem from oxygen vacancies but from other sources. The model strongly suggests that confinement effects should play a key role in shaping up magnetic properties of low dimension systems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interdiffusion effect on exchange coupling in annealing NiFe/FeMn and FeMn/NiFe systems
Authors: Chen Kuang‐Ching , Yang Cheng‐Ta , Wu Y. H. , Huang Chao‐Hsien , Wu Kuo‐Ming , Wu J. C. , Young S. L. , Horng Lance 
Published: December 2007

AbstractThe effect of interdiffusion on the exchange coupling field (Hex) and coercivity (Hc) in annealing NiFe/FeMn and FeMn/NiFe systems was investigated in the study. Type I samples: Silicon substrate/Ta/NiFe/FeMn/Ta and Type II samples: Silicon substrate/Ta/FeMn/NiFe/Ta were prepared. Annealing was carried out at 200 to 450 °C for two hours under 720 Oe, respectively. The results show that the Hex and Hc in two types samples were dependent on the annealing temperature. For both types the magnetization loss ratio (ΔM/MS) is negative, which reflects a loss of magnetization associated with interfacial mixing caused by annealing. The magnetization loss ratio becomes larger when the annealing temperature increases. The exchange coupling of these two types samples is associated with interfacial diffusion between the NiFe and FeMn interface. The annealing treatment also affected the Hc. In these two types samples, the exchange coupling was improved from modification of the interface between layers by annealing. The extended annealing (above 375 °C) changes the exchange coupling in these two types samples due to serious interdiffusion of the interface between NiFe and FeMn layers. It results in unwanted interdiffusion effects at the interface and a concomitant reduction in the exchange bias field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of monodisperse FePt@Au core‐shell nanoparticles
Authors: Wei D. H. , Hung D. S. , Ho C. S. , Wang J. W. , Yao Y. D. 
Published: December 2007

AbstractHydrophobic FePt@Au core‐shell nanoparticles were chemically synthesized and with controllable surface‐function properties. The enhanced optical property is due to the contribution of Au shell. The surface modification of FePt@Au nanoiparticles by using 11‐mercaptoundecanoic acid (MUA) was hydrophilic through ligand exchange and with good biocompatibility for future multi‐functional applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Annealing effect on magnetostatic properties of nanocomposite Fe‐Zr‐N films
Authors: Shalyguina E. , Sheftel E. , Usmanova G. , Mukasheva M. , Utitskich S. , Inoue M. , Fujikawa R. 
Published: December 2007

AbstractResults on the investigation of the magnetic properties and microstructure of the as‐deposited and annealed at T = 200‐700 °C Fe‐Zr‐N films are presented. The Fe‐Zr‐N films with the 0.7‐µm thickness were deposited by RF sputtering onto glass square substrates. Structural properties of the films were studied by means of the X‐ray diffraction technique. The bulk magnetic characteristics of the films have been measured by a vibrating sample magnetometer (VSM). The study of the near‐surface magnetic properties of the Fe‐Zr‐N samples was carried out employing magneto‐optical micromagnetometer with a surface sensitivity of about 20 nm of the thickness depth. The strong annealing effect on the values of the coercivity HC and the saturation field HS of the films was revealed. The values of HC and HS of the films, annealed at T = 450 and 500 °C, were found to be minimal. The temperature dependences of HC and HS were explained by microstructure changes of the studied films after their post‐deposition heat treatment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure of nanopores in AAO templates favoring the growth of nickel nanowires by electrodeposition
Authors: Jeong Jong‐Hyun , Kim Sun‐Hong , Choi Y. , Kim Sung‐Soo 
Published: December 2007

AbstractMorphology of periodical nanoscale pores in AAO templates has been studied in relation with anodizing process, focusing on the growth of nickel nanowires by electrochemical deposition. The AAO templates were prepared by a two‐step anodization process. The high purity aluminum plates were anodized in oxalic acid aqueous solution with variation of cell voltage. The pore size and interpore distance both increase with the applied potential. During the post treatment of barrier thinning, small‐size pores with split‐up structure at the tips are observed due to current‐limited anodizing process (decreasing cell potential). The rectifying properties of the barrier layer allow the pores to be filled by nickel by AC electrodeposition. The nickel nanowires array shows the ferromagnetic properties with a preferred magnetic orientation along the wire axis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Composition‐dependent magnetic properties of FePt nanoparticles synthesized by the SiO2‐nanoreactor method
Authors: Tamada Y. , Yamamoto S. , Takano M. , Nasu S. , Ono T. 
Published: December 2007

AbstractWe investigated effects of compostion on magnetic properties of FePt nanoparticles synthesized by the “SiO2‐nanoreactor” method in the composition range from Fe41Pt59 to Fe60Pt40. The magnetization studies implied that, in all samples, FePt nanoparticles can form the L10 structure although only a minor amount of unconverted precursor fcc‐FePt nanoparticles which behave superparamagnetic at room temperature still remained. It was revealed that composition of Fe54Pt46 has the smallest amount of the unconverted fcc‐FePt nanoparticles. Together with the results of composition‐dependence of coercivity, it can be concluded that slightly iron‐rich compositions is optimum to produce high quality L10‐FePt nanoparticles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Depinning field from notches on Co/Pd multilayer nanowires with perpendicular magnetic anisotropy
Authors: Choe Sug‐Bong 
Published: December 2007

AbstractDomain‐wall pinning and depinning mechanisms of ferromagnetc nanowires with perpendicular magnetic anisotropy were investigated. Micromagnetic simulation results revealed that the depinning field from notches were determined solely by the gap distance between the notches, irrespective to the wire width and the notch size. The double‐notch wires exhibited two‐fold décalcomanie domain patterns and one half patterns were identical to those of single‐notch wires. Therefore, the double‐notch wires showed the same depinning field compared to single‐notch wires with half width. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron‐spin‐resonance study on the size effects of La0.7Sr0.3MnO3 nanoparticles
Authors: Shih Yu‐Chou , Lin J. G. 
Published: December 2007

AbstractIn this work, a detailed analysis on the electron spin resonance (ESR) spectra within a broad temperature range (80‐400 K) is performed for studying the size effects of La0.7Sr0.3MnO3 nanoparticles synthesized by a sol‐gel route. Our ESR results reveal that La0.7Sr0.3MnO3 nanoparticles with grain sizes of 28 and 48 nm have two magnetic states below the Curie temperatures Tc, which is attributed to the different surface states. One is with the alligned surace spins, the other is with the disordered surface spins. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coercivity and microstructure of Mn–Ni–N sintered alloys
Authors: Sugimoto S. , Isogai K. , Hattori T. , Matsumoto H. , Yoshida S. , Tezuka N. 
Published: December 2007

AbstractThis paper describes the relationship between magnetic properties and microstructure in Mn‐Ni‐N sintered alloys. The Mn‐Ni‐N alloy heat‐treated at 1200 °C for 3 h and then jacket‐quenched in a nitrogen atmosphere, exhibits a high coercivity of 352 kAm‐1. The EDX analysis reveals that the sample jacket‐quenched and then annnealed in nitrogen, consists of two phases with different Ni content forming a lamellar structure. From TEM observations, the jacket‐quenched sample contains many stacking faults and twins with nano‐meter size. Therefore, it is considered that they play a role as pinning sites of domain wall motion and high coercivity observed with the quenched sample is casued by the domain wall pinning mechanism. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)