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1.
The process of magnetization reversal in Co
x
(PZT)100 − x
composites is studied experimentally. At room temperature, the ferromagnetic state in as-prepared samples is found to arise
only if the composite contains more than 60 at % of the metal phase. The concentration dependences of the coercive force and
remanent magnetization derived from magnetic hysteresis loops are discussed in terms of the random anisotropy model. 相似文献
2.
V. O. Vas’kovskii K. G. Balymov A. A. Yuvchenko A. V. Svalov A. N. Sorokin N. A. Kulesh 《Technical Physics》2011,56(7):981-985
The magnetization reversal and magnetoresistance of two-layer exchange-coupled Fe19Ni81/Tb-Co films are studied. Amorphous
Tb
x
Co100 − x
layers with 30 < x < 35 are found to have a uniaxial magnetic anisotropy and a rather high coercive force, which ensures magnetic biasing of
the adjacent permalloy layers. In addition, the permalloy layers subjected to selective annealing exhibit a significant anisotropic
magnetoresistance and a small magnetic hysteresis. These properties make it possible to consider the developed film structure
as an effective magnetoresistive medium. This structure is used to form magnetic sensor samples that have an odd transfer
function in the absence of external magnetic biasing. 相似文献
3.
Tadao Nozawa Fumio MorimotoRikio Harazono Norimoto Nouchi 《Journal of magnetism and magnetic materials》2006
The possibility of achieving soft magnetization in semi-hard magnetic films such as Fe, Fe93.5Si6.5, Fe50Co50 and Fe70Co30 is investigated by depositing films on an Fe20Ni80 underlayer by oblique-incidence evaporation. The magnetic anisotropy of the underlayer is strengthened to a depth of several lattice parameters by vapor deposition of the film at an oblique angle to the substrate surface. This method also allows magnetic anisotropy to be induced in strongly isotropic semi-hard magnetic overlayers to a thickness of a few thousands Angstroms. The coercive force of bilayer films measured along the hard-axis is reduced remarkably by this process, and the strength of the anisotropy field is demonstrated to be readily controllable. When magnetic anisotropy exists in both magnetic layers, a significant change is observed in the magnetization processes of the semi-hard magnetic layer and the coercive forces in the hard magnetization direction is dramatically reduced. Soft magnetization of the semi-hard magnetic layer cannot be achieved when magnetic anisotropy exists in only one of the magnetic layers. 相似文献
4.
The low-field magnetic properties of amorphous (Fe1?x Nix)80P10B10 are examined by measuring the local magnetic reversal field and the pinning field as function of position. Also measurements of magnetic anisotropy using FMR are reported. The observed magnetic behaviour is discussed generally. The magnetization reversal for the ideal parts of the wires may be described by the process of growth of nuclei present. 相似文献
5.
We report the observation of excellent hard magnetic properties on purely single phase ErCo7−xCux compounds with x=0.3, 0.5, 0.8 and 1. Cu substitution leads to a decrease in the saturation magnetization, but enhances the uniaxial anisotropy in this system. The large anisotropy field (∼100 kOe) is attributed to the Er and the Co sublattices. Domain wall pinning effect seems to play a crucial role in determining the temperature and field dependences of magnetization in these compounds. The hard magnetic properties obtained at room temperature (RT) are comparable to the best results obtained in other RCo7 based materials. 相似文献
6.
Zhicheng Zhang Qingyun WuKehua Zhong Shaofeng YangXuan Lin Zhigao Huang 《Journal of magnetism and magnetic materials》2006
Magnetization curves with various magnetic field orientations and nanowire diameters were measured at room temperature. The measured coercivity as a function of angle (θ) between the field and wire axis reveals that the coercivity decreases with increasing value of θ for various nanowires. Theoretically, based on Monte Carlo simulation we investigated the magnetization reversal modes of the Co1−xCux nanowires and obtained also the θ dependence of the coercivity. Comparing the simulated with the experimental results, we find that the magnetocrystalline anisotropy plays an important role on the magnetic properties of Co1−xCux nanowires, and the magnetization reversal process in the Co1−xCux nanowires could not be understood by the classical uniform rotation mode in the chain-of-sphere model. 相似文献
7.
K. V. Gon’kov K. A. Zvezdin A. V. Khvalkovsky 《Bulletin of the Lebedev Physics Institute》2008,35(8):238-243
Switching between right and left vortex magnetization states in annular ferromagnetic nanostructures, was studied. The study was performed by numerically solving the modified Landau-Lifshitz equation with consideration of the effect of spin transfer and full-scale consideration of the magnetostatic field, exchange energy, and anisotropy energy. The dynamics of magnetization reversal of the ferromagnetic nanoring, caused by the electric current flowing perpendicularly to the object plane and penetrating the structure, was studied taking into account two mechanisms of the current effect on magnetization: by the Oersted field and spin transfer. It was found that the presence of the spin polarization both perpendicular and parallel to the nanoring plane decreases the critical current at which the object is switched by an order of magnitude. It was shown that the toroidal moment \(\vec T\) is a convenient characteristic for describing magnetization reversal processes in annular magnetic nanostructures. 相似文献
8.
An effect of nonpolarized white light on the modulated magnetic structure of a FeBO3:Mg single crystal, which arises in this light-plane weak ferromagnet in the low temperature range during technical magnetization,
has been revealed. It has been found that the degree of the light action on the magnetic state of FeBO3:Mg depends both on its duration and on the orientation of the spontaneous magnetization vector M of the crystal during illumination. Interpretation of the results obtained has been performed in the context of the “magnetic
ripple” theory on the assumption that the absorbed light induces additional uniaxial magnetic anisotropy in the easy plane
of the crystal and that the anisotropy axis is collinear to the vector M during illumination. 相似文献
9.
We present theoretical analyses of anisotropic lattice diamagnetism, magnetization due to magnetic ions and carrier spin-polarization
in the diluted magnetic semiconductor, Pb1-x
Eu
x
Te. The lattice diamagnetism results from orbital susceptibility due to inter band effects and spin-orbit contributions. The
spin-orbit contribution is found to be dominant. However, both the contributions show pronounced anisotropy. With increase
in x, the diamagnetism decreases. We consider contributions from randomly distributed isolated magnetic ions and clusters of pairs
and triads for the local moment magnetization. The isolated magnetic-ion contribution is the dominant one.We calculate the
magnetization for two typical magnetic ion concentrations: x=0.03 and x=0.06. Temperature dependence of the magnetization is also considered. Apart from lattice and localized magnetic ions, the
carrier contribution to the spin-density is also calculated for a carrier density of p=1018 cm−3. the relative spin-density of carriers increases with increase in the magnetic field strength and magnetic ion concentration.
The agreement with experiment where available is reasonably good. 相似文献
10.
《Current Applied Physics》2020,20(9):1026-1030
We have comprehensively investigated asymmetric magnetization reversal behaviors of (x-Å Co/7.7 Å Pt)5 multilayers (x = 3.1 and 4.7) with perpendicular magnetic anisotropy. Our direct observation of magnetic domain structures by means of magneto-optical microscopy reveals that the asymmetry arises both from nucleation and wall-motion processes. An asymmetric nucleation behavior is observed, which could be originated from the preexisting non-reversed domains which might have a reproducible or random spatial distribution, controllable by tuning the field profile. An asymmetric wall-motion behavior stemming from asymmetric stripe domain evolution is also observed. 相似文献
11.
Based on the Monte Carlo simulation, the magnetic properties of the clusters, e.g. magnetization, Curie temperature, hysteresis, coercivity, natural angle and energy distribution etc., have been calculated. It has been found that, for the pure ferromagnetic cluster, the T3/2 Bloch law is well satisfied at low temperature (T < 0.5 TC) and Bsur is equal to 3 Bbulk. Meanwhile, there are clear indications that B increases drastically with the reducing atomic number Nwhich is consistent with the experimental facts. The results have been evalucted using the Bloch exponent law in the approximate crystalline approximation. It has also been demonstrated that the size dependence of the Curie temperature can be described by finite-size scaling theory. The investigation of the hysteresis and the spin configurations in different magnetization processes reveals the existence of an easy magnetization direction and anisotropy. The thermal coercivity for the clusters with zero and finite uniaxial anisotropy matches the experimental results well. The simulated results for the natural angle and energy distribution in the clusters prove further the existence of the configurational anisotropy in the clusters. It has been discussed that the natural angle and energy distribution influence the hysteresis of a cluster.Received: 10 September 2003, Published online: 15 March 2004PACS:
75.75. + a Magnetic properties of nanostructures - 75.40.Mg Numerical simulation studies - 75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects - 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.) 相似文献
12.
The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves
measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves
to determine the first- and second-order anisotropy constant in these films. In this paper we report a theoretical derivation
of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum
total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles
with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations
are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of
coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is
much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement
provides an effective access to analyze the in-plane anisotropy constant K
3 in hexagonal compounds, and the suitable experimental condition to measure K
3 is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2.
Supported by the National Natural Science Foundation of China (Grant Nos. 90505007 and 10774061)
Recommended by LI FaShen 相似文献
13.
Hysteresis loops and magnetic reversal processes have been determined by a three dimensional (3D) micromagnetic model for exchange-coupled Nd2Fe14B/α-Fe bilayers and carefully compared with a popular one-dimensional (1D) micromagnetic model. It is found that the calculated hysteresis loops, the critical fields and the magnetic phase diagrams agree well with the results given by the 1D model. However, the calculated nucleation mode is a quasi-curling one where the magnetic moment exhibits a curling in the film plane and varies in the thickness direction, in contrast with the reported quasi-coherent mode. The calculated spatial distribution of the magnetization orientation in the thickness direction at various applied fields signifies a three-step magnetic reversal process, which includes nucleation, growth and displacement of the domain wall as well as the rotation and the reversal of magnetization in the hard phase. The magnetic reversal of the hard phase is much slower than that given by the 1D model, leading to a more slant hysteresis loop near the coercivity point. 相似文献
14.
The frequency of orientational quantum oscillations of the magnetization near impurity-ion clusters with Ising properties
in a saturated magnetic crystal is calculated. It is noted that in compounds of the type HoxY3−x
Fe5O12, where magnetic phase transitions are observed, additional magnetization reversal and magnetic resonance features due to
mesoscopic oscillations of the magnetization can be observed at low concentrations x<0.001 and cryogenic temperatures in fields comparable to the intersublattice exchange interaction field.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 6, 445–448 (25 March 1997) 相似文献
15.
The Fe100-xMox(13≤x≤25) alloy nanowire arrays are synthesized by electrodeposition of Fe 2+ and Mo 2+ with different ionic ratios into the anodic aluminum oxide templates.The crystals of Fe100-xMox alloy nanowires gradually change from polycrystalline phase to amorphous phase with the increase of the Mo content and the nanowires are of amorphous structure when the Mo content reaches 25 at%,which are revealed by the X-ray diffraction and the selected area electron diffraction patterns.As the Mo content increases,the magnetic hysteresis loops of Fe100-xMox alloy nanowires in parallel to the nanowire axis are not rectangular and the slopes of magnetic hysteresis loops increase.Those results indicate that the magnetostatic interactions between nanowires and the magnetocrystalline anisotropy both have significant influences on the magnetization reversal process of the nanowire arrays. 相似文献
16.
M. Guillot A. Marchand J. M. Desvignes H. Le Gall T. Merceron M. Guillaud 《Zeitschrift für Physik B Condensed Matter》1989,74(3):335-339
Magnetization measurements in d.c. magnetic fields up to 180 kOe have been performed on polycrystalline specimens and on single crystals of mixed terbium-yttrium iron garnets: Tb
x
Y3–x
Fe5O12 in the 4.2–300 K temperature range. On polycrystals (x=2.5; 2; 1; 0.37) the concentration dependence of both compensation point and spontaneous magnetization has been determined. In the single crystals (x=2; 1; 0.37) a strong magnetic anisotropy has been observed with a change of the easy direction of magnetization from [111] to [100] whenx decreases; abrupt field-induced transitions have been observed at low temperatures when the external field is applied along the [100] direction. 相似文献
17.
Hao-Liang LiuWei He Hai-Feng DuQiong Wu Ya-Peng FangYun Zhu Jian-Wang CaiZhao-Hua Cheng 《Journal of magnetism and magnetic materials》2011,323(17):2238-2242
We present the experimental results on thermally activated magnetization reversal for [Co0.9Fe0.1(5.0 Å)/Pt(20 Å)]4 multilayer. Direct domain observations show that magnetization reversal is initiated with rare nucleation and followed by dendritic growth of domain walls. Based on macroscopic magnetic parameters from experimental data, the dendritic domain growth mode is qualitatively interpreted by Monte Carlo simulations in terms of a simple uniaxial magnetic anisotropy model. Moreover, both time evolution of domain growth observation and magnetic relaxation measurements reveal that CoFe/Pt multilayer has a relatively large activation volume compared with Co/Pt multilayers. 相似文献
18.
I. O. Troyanchuk N. V. Samsonenko G. Shimchak A. Nabyalek 《Physics of the Solid State》1997,39(1):101-103
The magnetic properties of Eu1−x
CaxMnO3 have been investigated. As the calcium content increased up to x=0.2, the magnetization and the blocking temperature of the magnetic moments of clusters increased and the magnetic anisotropy
decreased. As the calcium content increased further, the magnetization decreased, while the “freezing” temperature of the
magnetic moments increased. Anomalies of the magnetic properties were observed in compositions with x=0.4 and 0.5 at T=40 K; these anomalies are attributed to a transition to the antiferromagnetic state in the charge-ordered phase.
Fiz. Tverd. Tela (St. Petersburg) 39, 117–120 (January 1997) 相似文献
19.
E. N. Il’icheva A. V. Klushina N. B. Shirokova N. N. Ustanov A. G. Shishkov 《Technical Physics》1997,42(6):615-618
An experimental study is made of the effect of an in-plane field H
p
of various orientations on the domain structure and shape of the hysteresis loops of epitaxial iron garnet films with the
(210) orientation. The characteristic of the magnetization reversal process (in fields somewhat lower than the anisotropy
field) is taken to be the critical fields H
p1, H
p2, and H
p3, for which the magnetization reversal processes is interrupted at distinct stages. A method is proposed for constructing
the phase diagram of the magnetic states of films, using measurements of the critical fields H
p
for different amplitudes of the magnetization reversal field H
z
. Two directions in the plane of the film are determined with an accuracy of a fraction of a degree from the hysteresis loops,
where in the corresponding field Hp the transition from a single-domain state to a multidomain state occurs as a second-order phase transition. The characteristic
changes in the shape of the hysteresis loop are consistent with the features in the reorganization of the domain structure
of the (210) film. The preferential orientations of the stripe domain structure of the samples are determined relative to
the crystal axes as determined by x-ray methods.
Zh. Tekh. Fiz. 67, 32–35 (June 1997)
Deceased 相似文献
20.
Yu. P. Ivanov A. I. Il’in E. V. Pustovalov L. A. Chebotkevich 《Physics of the Solid State》2010,52(8):1694-1700
The magnetic structure and the processes of magnetization reversal of individual cobalt nanodots and arrays of cobalt nanodots
have been studied using the magneto-optical Kerr effect and magnetic force microscopy. Arrays of nanodots have been prepared
by ion etching from a continuous cobalt film. Magnetic anisotropy is induced during deposition of the cobalt films. The nanodots
have the diameter d = 600 nm and the period varying from 1.5d to 3.0d. Magnetic force microscopy images have shown that the induced magnetic anisotropy affects the orientation of magnetization
of noninteracting nanodots and the direction of displacement of the magnetic vortex center in the nanodots coupled by the
dipole-dipole interaction. 相似文献