jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Apr 2010

Volume 107, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

J. Appl. Phys. 107, 081101 (2010); http://dx.doi.org/10.1063/1.3340792 (15 pages)

Anne-Marie Kietzig, Savvas G. Hatzikiriakos, and Peter Englezos
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds
back to top Magnetism and Superconductivity

Electric-field modulation of magnetic properties of Fe films directly grown on BiScO3–PbTiO3 ceramics

Jing Wang, Jiamian Hu, Han Wang, He Jiang, Zhangben Wu, Jing Ma, Xiaohui Wang, Yuanhua Lin, and C. W. Nan

J. Appl. Phys. 107, 083901 (2010); http://dx.doi.org/10.1063/1.3369284 (5 pages) | Cited 5 times

Online Publication Date: 19 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An electric-field modulation of the magnetic properties through converse magnetoelectric effect was reported in Fe films directly grown on BiScO3–PbTiO3 (BSPT) ceramics based on the magneto-optical Kerr effect. When an electric field was applied on the piezoelectric BSPT ceramics, the coercive field (Hc) of the ferromagnetic Fe films changed dramatically and an upto 60% change in Hc was observed. The Hc electric field curve essentially tracked the dependence of the piezostrain of the BSPT ceramics on the electric field, which definitely demonstrated the magnetic-mechanical-electric coupling in such film-on-substrate composite structures.
Show PACS
78.20.Ls Magneto-optical effects
75.85.+t Magnetoelectric effects, multiferroics
77.65.-j Piezoelectricity and electromechanical effects
75.50.Bb Fe and its alloys
77.55.Nv Multiferroic/magnetoelectric films

Hysteretic giant magnetoresistance curves induced by interlayer magnetostatic coupling in [Pd/Co]/Cu/Co/Cu/[Co/Pd] dual spin valves

P. Y. Yang, X. Y. Zhu, G. Chen, F. Zeng, and F. Pan

J. Appl. Phys. 107, 083902 (2010); http://dx.doi.org/10.1063/1.3385314 (5 pages) | Cited 4 times

Online Publication Date: 19 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The giant magnetoresistance (GMR) characteristics of hybrid perpendicular/Cu/in-plane magnetic anisotropy [Pd/Co]/Cu/Co single spin valves and [Pd/Co]/Cu/Co/Cu/[Co/Pd] dual spin valves with applied field perpendicular and parallel to the film plane are studied. Linear and nonhysteretic GMR behaviors are observed for the two spin valves in perpendicular-to-plane applied fields due to the coherent rotation of the Co layer driven by the in-plane shape anisotropy. The GMR value of the dual spin valve is 1.8 times as large as that of the single spin valve. The correlations between the magnetic configuration of the devices and the resistance evolvement are analyzed. In-plane GMR curves with maximum applied field of 30 kOe deviate from the linear behavior and can be well described by the Stoner–Wohlfarth model including high order anisotropy terms. Moreover, obvious hysteresis behavior is observed in the in-plane GMR curve of the dual spin valve. This phenomenon results from the hindered rotation of the Co/Pd moments due to the magnetostatic coupling between the top and bottom Co/Pd multilayers in the dual spin valve.
Show PACS
75.47.De Giant magnetoresistance
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.78.-n Magnetization dynamics

Pressure effects on superconductivity of Fe1+yTe1−xSx single crystals

Z. T. Zhang, Z. R. Yang, L. Li, L. Pi, S. Tan, and Y. H. Zhang

J. Appl. Phys. 107, 083903 (2010); http://dx.doi.org/10.1063/1.3385392 (3 pages) | Cited 4 times

Online Publication Date: 19 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the pressure effect on superconductivity of Fe1+yTe1−xSx single crystals. We show that the applied pressure leads to opposite variation in the superconductivity between homogeneous and inhomogeneous samples. With increasing pressure to 10 kbar, the superconductivity of homogenous sample S1 is suppressed gradually, however Tcmag of inhomogeneous S4 can be raised up to 21 K. The increase in Tcmag in S4 is believed as stabilizing the structure by strain effect in inhomogeneous sample, thereby avoiding structural transition under pressure. Our results imply that higher Tc could be expected in iron chalcogenides if this structural instability could be suppressed.
Show PACS
74.62.Fj Effects of pressure
74.81.-g Inhomogeneous superconductors and superconducting systems, including electronic inhomogeneities
74.25.fc Electric and thermal conductivity
74.25.Ha Magnetic properties including vortex structures and related phenomena
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
61.66.Fn Inorganic compounds

Prediction of variation in critical current with applied tensile/bending strain of Bi2223 composite tape from tensile stress-strain curve

S. Ochiai, H. Okuda, M. Sugano, M. Hojo, and K. Osamura

J. Appl. Phys. 107, 083904 (2010); http://dx.doi.org/10.1063/1.3380828 (9 pages) | Cited 3 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An approach to predict the variation in critical current with applied tensile/bending strain of Bi2223/Ag/Ag alloy composite tapes from the tensile stress-strain curves was presented. Three different fabrication-route samples were used to examine the applicability of the present approach. The damage strain parameter, referring to the difference between the tensile fracture strain and residual strain of Bi2223 filaments along the sample length direction (current transport direction), was estimated from the variation in the slope of the tensile stress-strain curve. With the estimated damage strain parameter, the irreversible tensile strain for critical current was predicted, which agreed well with the experimental result in all samples. Also by substituting the estimated damage strain parameter into the core shape—incorporated model, the critical current-bending strain curve was predicted, which described satisfactorily the experimental result in all samples. The present approach could be a useful tool for prediction of critical current-dependence on applied tensile/bending strain.
Show PACS
74.25.Sv Critical currents
74.70.-b Superconducting materials other than cuprates
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations

Structural, electrical, magnetic, and thermal studies of Cr-doped La0.7Ca0.3Mn1−xCrxO3 (0 ≤ x ≤ 1) manganites

Neeraj Kumar, H. Kishan, Ashok Rao, and V. P. S. Awana

J. Appl. Phys. 107, 083905 (2010); http://dx.doi.org/10.1063/1.3342462 (6 pages) | Cited 6 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report detailed structural, electrical, magnetic, and specific heat studies on La0.7Ca0.3Mn1−xCrxO3 manganites. Rietveld analysis of fitted and observed x-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in Pbnm space group. Successive substitution of Cr at Mn-site in La0.7Ca0.3Mn1−xCrxO3 manganites increases the electrical resistivity and decreases the characteristic insulator-metal transition temperature (TIM) of the parent compound along with a humplike feature for higher Cr-content (x>0.06) samples. The hump structure basically signifies the onset of antiferromagnetic (AFM) interactions as inferred by both the magnetic and infrared (IR) spectroscopy studies. The systematic suppression of FM state results in a spin glass (SG)-like behavior. IR studies revealed that the vibration mode at 413 cm−1 being associated with internal bending of MnO6 octahedra, becomes softer, indicating an increase in distortion and hence the possible SG behavior. The critical exponents (α, β, and γ) are calculated from the heat capacity (CP) data near the TIM/TFM. The same exhibited variations of their values with doping. In particular, the value of β increases from 0.37(x = 0.0) to 0.43(x = 0.04), clearly indicating the coexistence of both long and short range magnetic orders, i.e., tendency toward SG state for Cr-doped samples. On the basis of present results, it is suggested that Cr dilutes double-exchange based FM and rather promotes the AFM based superexchange interactions via Cr3+/Mn4+ ions. Substitution of Cr systematically destroys both the metallic state and long range FM order.
Show PACS
61.66.Fn Inorganic compounds
75.50.Ee Antiferromagnetics
75.30.Et Exchange and superexchange interactions
65.40.Ba Heat capacity
75.47.Lx Magnetic oxides
72.20.My Galvanomagnetic and other magnetotransport effects

Calculation of complex permeability of magnetic composite materials using ferromagnetic resonance model

C. P. Neo, Y. Yang, and J. Ding

J. Appl. Phys. 107, 083906 (2010); http://dx.doi.org/10.1063/1.3383054 (6 pages) | Cited 2 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Landau–Lifshitz–Gilbert (LL-G) formula has been widely used in modeling of complex permeability of magnetic thin films and particle composites. In this paper, a approach which is based on Landau–Lifshitz ferromagnetic resonance (LL-FMR) model has been developed to calculate the complex permeability of magnetic particles/insulator matrix composite. It has found that the LL-FMR model can be used to compute the intrinsic permeability of a magnetic particle with different alignments of its magnetic domains with the respect to the incident wave. Through integration with respect to its resonant frequency, this method offers a neat closed-form formula for the case of isotropic composite. Its results compared relatively well with our previous method which computes the isotropic permeability by taking the average of the permeability of a large number of randomly oriented magnetic domains with respect to incident wave based on the LL-G model. For carbonyl bcc-Fe and Fe3O4, the calculated permeability agrees relatively well with the measurement results.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Tt Fine-particle systems; nanocrystalline materials
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.60.Ch Domain walls and domain structure
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Demagnetization process and hysteresis loops in perpendicularly oriented hard/soft trilayers

G. P. Zhao, N. Bo, H. W. Zhang, Y. P. Feng, and Y. Deng

J. Appl. Phys. 107, 083907 (2010); http://dx.doi.org/10.1063/1.3356984 (6 pages) | Cited 4 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nucleation and evolution of domain walls as well as the magnetic reversal process in perpendicularly oriented hard/soft trilayers have been investigated within a micromagnetic approach, concentrated on the situation with very thin hard layer. The formula for the nucleation field has been derived, which falls as the soft layer thickness rises. Negative nucleation field occurs at thick soft layer when the shape anisotropy surpasses the crystalline one, where the magnetization in the center of the soft layer obeys the coherent rotation model. The microscopic and macroscopic hysteresis loops have been calculated numerically, with the angular distribution of the magnetization between the nucleation and pinning fields obtained. The area of the hysteresis loop decreases while the coercivity mechanism changes from nucleation to pinning as the soft layer thickness increases. The effect of the hard layer thickness is contrary to that of the soft layer, however, the former affects the demagnetization process and hysteresis loops significantly only when the layers are thin enough.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Jk Magnetization reversal mechanisms
75.60.Ch Domain walls and domain structure
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.78.Cd Micromagnetic simulations
75.50.Vv High coercivity materials

Effect of excess Fe on the superconducting and magnetic properties of the FeTe0.70Se0.30 compound

C. S. Yadav and P. L. Paulose

J. Appl. Phys. 107, 083908 (2010); http://dx.doi.org/10.1063/1.3392797 (3 pages) | Cited 5 times

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the properties of stoichiometric FeTe0.7Se0.3 and the effect of Fe excess in this system. The excess Fe compound is shown to display spin glasslike order below 26 K. Microscopic studies using 57Fe Mössbauer spectroscopy show the gradual evolution of the magnetic hyperfine field below the spin glass order. The dc magnetization and hyperfine field distribution show that there is a strong moment on the Fe in this system.
Show PACS
74.25.Ha Magnetic properties including vortex structures and related phenomena
75.50.Lk Spin glasses and other random magnets
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.Bt Thermodynamic properties
74.25.F- Transport properties

Persistent supercurrents in ring-shaped Bi2Sr2CaCu2Ox single crystal

Rongchao Ma, A. I. Mansour, M. Egilmez, C. E. Winterfield, I. Fan, K. H. Chow, J. Jung, D. Prabhakaran, and F. Razavi

J. Appl. Phys. 107, 083909 (2010); http://dx.doi.org/10.1063/1.3374661 (4 pages)

Online Publication Date: 21 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A superconducting ring could be used to simulate the supercurrent conduction, and its interaction with magnetic vortices in a superconducting solenoid, allowing one to investigate the nature of the vortex structure and its pinning in the presence of the persistent supercurrent. The dissipation of the persistent supercurrent has been studied in a ring-shaped high purity single crystal of Bi2Sr2CaCu2Ox in order to obtain the information about the exponent μ, a parameter in the scaling relation between the effective energy barrier against vortex motion Ueff and the persistent current density J. The measurements of the persistent supercurrent decay show a transition from a strongly nonlogarithmic to a logarithmic decay regime with an increasing temperature. In response to a small increase in the concentration of oxygen vacancies μ decreases in the logarithmic decay regime but remains almost constant in the nonlogarithmic one.
Show PACS
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
74.72.-h Cuprate superconductors

Effect of Sn substitution on the para-conductivity of polycrystalline Cu0.5Tl0.5Ba2Ca2Cu3−ySnyO10−δ superconductors

Nawazish Ali Khan, Najmul Hassan, Sana Nawaz, Babar Shabbir, Sajid Khan, and Azhar A. Rizvi

J. Appl. Phys. 107, 083910 (2010); http://dx.doi.org/10.1063/1.3357278 (7 pages) | Cited 1 time

Online Publication Date: 22 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High quality electrical resistivity ρ(T) versus temperature data of as-prepared and O2-annealed Cu0.5Tl0.5Ba2Ca2Cu3−ySnyO10−δ (y = 0, 0.25, 0.5, 0.75, 1.0, 1.25, and 1.5) superconductors has been studied for fluctuation-induced phenomena setting in at temperatures well above the critical temperature [Tc(R = 0)]. The analysis of the data is done by using Aslamazov–Larkin (AL) and Lawrence–Doniach models for the excess conductivity. We have estimated several physical parameters, including coherence length, interplane coupling strength, exponents, and dimensionality of the fluctuations. The as-prepared and oxygen postannealed samples have shown a cross-over temperature associated with two distinct exponents and the excess conductivity data fits well with the two-dimensional and three-dimensional AL equations. The coherence length along the c-axis [ξc(0)] and the interlayer coupling strength (J) are found to decrease with increased Sn doping. These values are increased after annealing the samples in oxygen atmosphere, which is most likely associated with the approach of carrier concentration in the conducting CuO2/SnO2 planes to the optimum value. The Tc(R = 0) and the peak temperature (TP) as determined from the dρ/dT versus temperature plots are also found to decrease with increased Sn substitution, however, these temperatures are improved to higher values after annealing the samples in oxygen atmosphere. The decreased values of Tc(R = 0) and TP with increased Sn substitution in the as-prepared samples are most likely arising from the suppression of carrier’s density promoted by the increased volume of unit cell and the localization of the carriers at the Sn4+ sites.
Show PACS
74.25.fc Electric and thermal conductivity
74.10.+v Occurrence, potential candidates
74.62.Dh Effects of crystal defects, doping and substitution
74.25.Ha Magnetic properties including vortex structures and related phenomena
74.40.-n Fluctuation phenomena
74.72.-h Cuprate superconductors

Magnetic states and magnetization reversal in magnetostatically coupled multilayers with low perpendicular anisotropy

M. Tekielak, M. Dąbrowski, M. Kisielewski, A. Maziewski, and V. Zablotskii

J. Appl. Phys. 107, 083911 (2010); http://dx.doi.org/10.1063/1.3327429 (9 pages) | Cited 5 times

Online Publication Date: 22 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Multilayers of (F/NF)N composition, where F means a ferromagnetic layer, NF a nonferromagnetic one, and N the number of repetitions, are studied by simulations and theoretically for different magnetic anisotropy characterized by the quality factor, Q (the ratio of the anisotropy energy to be gained by a magnetization along the easy axis perpendicular to the sample surface and the magnetostatic energy of a uniformly magnetized layer along the surface normal). It is shown that the range of the existence of out-of-plane magnetization states could be extended to Q<1 by proper choice of N and the layers thicknesses. The role of magnetostatic interlayer coupling in the formation of vortexlike and sinusoidal-like distributions of the magnetization is revealed. Different magnetization states are mapped onto a (Q,N)-phase diagram. We demonstrate that a (F/NF)N multilayer is a soft magnetic system in which the domain size could be changed by a few orders of magnitude by small variations of Q, N, and/or the NF spacer thickness. The evolution of magnetization distributions under applied in-plane and perpendicular magnetic fields is studied, as well as calculating the saturation fields and their dependences on Q and N.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.60.Jk Magnetization reversal mechanisms
75.30.Gw Magnetic anisotropy

Effect of light rare earth element Nd doping on magnetization dynamics in Co–Nb films

Zhengmei Zhang, Min Lin, Jingyi Zhu, Dangwei Guo, Guozhi Chai, Xiaolong Fan, Yuancai Yang, and Desheng Xue

J. Appl. Phys. 107, 083912 (2010); http://dx.doi.org/10.1063/1.3383044 (4 pages) | Cited 1 time

Online Publication Date: 23 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
(Co0.85Nb0.15)100−xNdx (x = 0, 1.1, 3.4, and 6.4) soft magnetic thin films have been prepared on Si substrates by oblique sputtering ∼ 16°. The dynamic properties of the films were systematically investigated in a wide frequency range from 0.1 to 7 GHz. Strong enhancement of the damping parameter which is one key materials parameter that controls the dynamic response and the full width at half maximum of the imaginary permeability spectra were observed when Nd element was doped. The fitted value of the damping parameter for (Co0.85Nb0.15)93.6Nd6.4 film is around 0.1, which is almost one order larger than that 0.015 of (Co0.85Nb0.15)100 film.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.15.Cd Deposition by sputtering
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.78.-n Magnetization dynamics

The effect of grain boundaries on the domain wall dynamics in Pr1−xAgxMnO3 manganites

Hossein Ahmadvand, Hadi Salamati, and Parviz Kameli

J. Appl. Phys. 107, 083913 (2010); http://dx.doi.org/10.1063/1.3383024 (7 pages) | Cited 1 time

Online Publication Date: 26 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We performed detailed ac susceptibility measurements on Pr1−xAgxMnO3 (x = 0.15,0.20) manganites and observed unusual and interesting features, which are associated with the domain walls and the effects of grain-boundaries on their movements. It is shown that the ac field, frequency, temperature, thermal cycling, and grain coupling significantly influence the real and especially imaginary parts of the ac susceptibility. We argue that the cooperative depinning of the domain walls from the grain-boundaries accompanying with a large distance movements of the walls leads to the appearance of an anomaly at low temperatures. The anomaly is observed above a threshold ac field and depends on the intergrain coupling. The results show that in the powdered form of bulk samples, the anomaly disappears and the ac field dependence of the χ′ and χ″ suppresses. Below the anomaly temperature, significant and unusual thermal hysteresis occurs in the real and especially imaginary parts of the ac susceptibility. Thermal hysteresis depends on the thermal cycling and indicates thermally irreversible wall pinning and depinning. The susceptibility is practically frequency-independent in the temperature range of thermal hysteresis, i.e., below the anomaly. The frequency dependence of the ac susceptibility between the anomaly temperature and the transition temperature is discussed by considering the temperature dependence of the relaxation process of the domain walls.
Show PACS
75.78.Fg Dynamics of domain structures
75.30.Cr Saturation moments and magnetic susceptibilities
61.72.Mm Grain and twin boundaries
75.60.Ch Domain walls and domain structure

Low temperature noncollinear behavior in ultrathin Fe/Al multilayer structures

R. Brajpuriya

J. Appl. Phys. 107, 083914 (2010); http://dx.doi.org/10.1063/1.3383049 (6 pages)

Online Publication Date: 26 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the low temperature noncollinear magnetic behavior of electron beam evaporated ultrathin Fe/Al multilayer (ML) structures. Investigations have been carried out with ML samples with Fe-layer thicknesses in a range of 10–40 Å and Al-layer thickness of 10 Å. The structural studies show that heavy atomic interdiffusion between Fe and Al layers occurs at the interface, resulting MLs of different complicated structures according to different sublayer thicknesses Brajpuriya, et al.., [Eur. Phys. J. B 51, 131 (2006) ]. The magnetic measurements show that these films are “re-entrant” systems and not ordinary ferromagnets as often assumed. The obtained results, interestingly, indicate a transition from ferromagnetic state to a low temperature disordered state where a collective frozen magnetic state with grain moments oriented randomly occurs. We interpret the observed low temperature noncollinear magnetic behavior to be due to random freezing of grain moments.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.15.Dj E-beam and hot filament evaporation deposition
75.30.Cr Saturation moments and magnetic susceptibilities
66.30.Ny Chemical interdiffusion; diffusion barriers
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Motion of transverse domain walls in thin magnetic nanostripes under transverse magnetic fields

J. Lu and X. R. Wang

J. Appl. Phys. 107, 083915 (2010); http://dx.doi.org/10.1063/1.3386468 (9 pages) | Cited 6 times

Online Publication Date: 27 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The motion of transverse magnetic domain walls (TDW) in thin magnetic nanostripes under transverse magnetic fields (TMF) is investigated. In the absence of axial fields, an approximate static TDW profile is obtained under a TMF with an arbitrary orientation. This profile becomes exact if the TMF is parallel or perpendicular to the stripe plane. Under nonzero axial fields, the TDW becomes asymmetric and twisted, and it moves along the wire axis with two different propagation modes, rigid-body mode and precession mode, depending on the strength of the axial field. The critical strength separating these two modes is called modified Walker limit HW′. The TMF dependence of HW′, the TDW velocity and maximum twisting angle at HW′ were investigated both numerically and analytically. Moreover, it is shown that an early proposed velocity-field relationship fits well to the average velocities of a TDW above HW′. These results should be important for future developments of magnetic nanodevices based on DW propagation.
Show PACS
75.60.Ch Domain walls and domain structure
75.50.Tt Fine-particle systems; nanocrystalline materials
75.75.-c Magnetic properties of nanostructures

Structure and magnetic properties of nanocrystalline PrCo3

K. Younsi, V. Russier, and L. Bessais

J. Appl. Phys. 107, 083916 (2010); http://dx.doi.org/10.1063/1.3388364 (7 pages) | Cited 10 times

Online Publication Date: 27 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structure and magnetic properties of nanocrystalline PrCo3 prepared by high-energy milling technique have been investigated by means of x-ray diffraction using the Rietveld method coupled to Curie temperature and magnetic measurements. The as-milled samples were subsequently annealed in temperature range from 750 to 1050 °C for 30 min to optimize the extrinsic properties. From x-ray studies of magnetic aligned samples, the magnetic anisotropy of this compounds is found uniaxial. The Curie temperature is 349 K and no saturation reached at room temperature for applied field of 90 kOe. The coercive field of 55 kOe and 12 kOe measured at 10 K and 293 K, respectively is obtained after annealing at 750 °C for 30 min suggests that nanocrystalline PrCo3 are interesting candidates in the field of permanent magnets. We have completed this experimental study by simulations in the micromagnetic framework in order to get a qualitative picture of the microstructure effect on the macroscopic magnetization curve. From this simple model calculation, we can suggest that the after annealing the system behaves as magnetically hard crystallites embedded in a weakly magnetized amorphous matrix.
Show PACS
75.30.Gw Magnetic anisotropy
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
81.05.Bx Metals, semimetals, and alloys
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
75.78.Cd Micromagnetic simulations
61.46.Hk Nanocrystals
75.75.Cd Fabrication of magnetic nanostructures

Experimental and theoretical response of distributed read-out imaging devices with imperfect charge confinement

R. A. Hijmering, A. G. Kozorezov, P. Verhoeve, D. D. E. Martin, J. K. Wigmore, R. Venn, and P. J. Groot

J. Appl. Phys. 107, 083917 (2010); http://dx.doi.org/10.1063/1.3327412 (10 pages)

Online Publication Date: 28 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a model to describe the responsivity of distributed read-out imaging devices following photon absorption in the absorber or in the base or top film of the superconducting tunnel junctions at either end of the absorber. The model describes the processes most relevant for photon detection, taking into account diffusion of quasiparticles across the absorber and imperfect confinement in the superconducting tunnel junctions via exchange of quasiparticles between absorber and the junction. It incorporates diffusion mismatch between superconducting tunnel junction and absorber, possible asymmetry between the two junctions and asymmetry between base and top electrodes within each junction. We have conducted dedicated experiments in which different experimental conditions were varied in order to test the model. A good agreement was found between the experimental results and model predictions.
Show PACS
74.50.+r Tunneling phenomena; Josephson effects
85.25.Oj Superconducting optical, X-ray, and γ-ray detectors (SIS, NIS, transition edge)
07.60.Dq Photometers, radiometers, and colorimeters

Magnetic and transport properties in ordered arrays of permalloy antidots and thin films

G. A. Badini Confalonieri, K. R. Pirota, M. Vazquez, N. M. Nemes, M. Garcia-Hernandez, M. Knobel, and F. Batallan

J. Appl. Phys. 107, 083918 (2010); http://dx.doi.org/10.1063/1.3383039 (5 pages) | Cited 4 times

Online Publication Date: 29 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetotransport behaviors of two types of permalloy nanostructures, thin films and antidots, are presented and discussed. Antidots samples were prepared by sputtering a Ni80Fe20 layer on top of a nanoporous alumina membrane. A counterpart continuous thin film grown on a continuous Si substrate was also prepared. The magnetoresistance (MR) was measured both as a function of the external applied magnetic field and of the angular orientation, and thus compared with the magnetization curves. The introduction of antidots is found to reduce the anisotropic MR and the angular dependence of the MR, simultaneously increasing the coercive field of the samples. The influence of the sample geometry on the perpendicular MR behavior is reported and discussed.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.47.Np Metals and alloys
75.30.Gw Magnetic anisotropy
73.63.Kv Quantum dots

Magnetic properties of nickel hydroxide nanoparticles

X. H. Liu, W. Liu, X. K. Lv, F. Yang, X. Wei, Z. D. Zhang, and D. J. Sellmyer

J. Appl. Phys. 107, 083919 (2010); http://dx.doi.org/10.1063/1.3374468 (3 pages) | Cited 6 times

Online Publication Date: 29 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetic properties of 10 nm size Ni(OH)2 nanoparticles prepared by sol-gel method have been studied. The magnetic moments increase with decreasing temperature in a low applied field, which is due to the spin-frozen-like state at low temperatures, and the metamagnetic transition is not clearly observed even in an applied field of 70 kOe due to the size effect. Furthermore, the transition from paramagnetic to antiferromagnetic in the Ni(OH)2 nanoparticles occurs at lower temperature (22 K).
Show PACS
75.75.Cd Fabrication of magnetic nanostructures
81.07.Wx Nanopowders
75.50.Tt Fine-particle systems; nanocrystalline materials
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.30.Cr Saturation moments and magnetic susceptibilities

Giant tunneling magnetoresistance with electron beam evaporated MgO barrier and CoFeB electrodes

H. Kurt, K. Oguz, T. Niizeki, and J. M. D. Coey

J. Appl. Phys. 107, 083920 (2010); http://dx.doi.org/10.1063/1.3371811 (6 pages) | Cited 9 times

Online Publication Date: 30 April 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron-beam (EB) evaporated MgO grows with (001) texture on amorphous CoFeB when the deposition rate is kept below 5 pm/s. Magnetic tunnel junctions (MTJs) fabricated using this method exhibit ∼ 240% magnetoresistance at room temperature for a 2.5 nm thick EB-MgO barrier, which is similar to the value for a radio frequency (rf) sputtered barrier with the same junction geometry. The average barrier height of the EB-MgO is 0.48 eV, which is higher than previously reported values for rf-MgO barriers and it increases with increasing annealing temperature. Our results show that EB-MgO could be a simpler alternative to rf-MgO in MTJs without any compromise in the tunnelling magnetoresistance.
Show PACS
75.47.De Giant magnetoresistance
75.50.Kj Amorphous and quasicrystalline magnetic materials
81.15.Dj E-beam and hot filament evaporation deposition
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close