共查询到20条相似文献,搜索用时 31 毫秒
1.
The interaction of a vortex-like domain wall moving in an external magnetic field with a three-dimensional periodic chain of cubic volumes with high values of the saturation magnetization and magnetic anisotropy constant has been investigated theoretically. It has been found that the result of the interaction depends on the initial distance between the wall and the region of inhomogeneity of magnetic parameters at the moment of turning on the external magnetic field. The pinning of domain walls near the regions with high values of the saturation magnetization and magnetic anisotropy constant has been investigated, and the anisotropy of the corresponding depinning fields has been revealed. The method of investigation is the numerical micromagnetic simulation. 相似文献
2.
Yu. A. Fridman D. A. Matyunin F. N. Klevets G. A. Gorelikov 《Physics of the Solid State》2010,52(6):1196-1203
The possibility of forming a modulated (spiral) magnetic structure in anisotropic Heisenberg and non-Heisenberg magnets with
a frustrated Heisenberg exchange interaction has been investigated. It has been demonstrated that, apart from homogeneous
(ferromagnetic and quadrupole) states, the Heisenberg magnets with a strong easy-plane anisotropy can have a spiral magnetic
structure. The axis of the spiral coincides with the direction of the external magnetic field. The inclusion of the biquadratic
exchange interaction leads to a narrowing of the magnetic field region of the existence of the spiral structure. In the absence
of the external magnetic field, the spiral structure can be formed only in the case of easy-axis anisotropy. 相似文献
3.
The magnetization behavior and the magnetic entropy change of a system made up of ferromagnetically interacting particles are calculated by using Monte Carlo simulation. The effect of the magnetic anisotropy of particles and the dipolar–dipolar interaction between particles on the magnetization and the magnetic entropy change of the system are discussed. It is found that there is no spontaneous magnetization, both the magnetic anisotropy of particles and the dipolar–dipolar interaction between particles restrains the system's magnetizing in the external magnetic field. The magnetic entropy change decreases with the increase in temperature in the system without the dipolar–dipolar interaction; however, the dipolar–dipolar interaction between particles makes the magnetic entropy change of the system have maximum value at low temperatures. 相似文献
4.
Hai-Jun Wang Yuan Chen Liang-Jie Fu Rui-Na Lin Chuang-Chuang Song 《Journal of magnetism and magnetic materials》2009,321(12):1904-1908
One-dimensional single-ion anisotropic ferromagnet with spin-1 is investigated by means of Green's function treatment in this paper. The model Hamiltonian includes a Heisenberg ferromagnetic term, an external magnetic field, and a second-order single-ion anisotropy. The magnetic properties of the system are treated by the random phase approximation for the exchange interaction term and the Anderson-Callen approximation for the anisotropy term. Our paramagnetic results are in agreement with the other theoretical results. 相似文献
5.
We investigate the properties of spin-orbit interaction in the ground state and thermal entanglement of a two-qutrit Heisenberg XYZ system in the presence of an inhomogeneous magnetic field. Using negativity as entanglement measure, we give the dependence of entanglement on each parameter in detail. The result shows that one can get appropriate entanglement by adjusting the magnetic field, Dzyaloshinskii-Moriya interaction and anisotropy parameter simultaneously. 相似文献
6.
We investigate the properties of spin-orbit interaction in the ground state and thermal entanglement of a two-qutrit Heisenberg XYZ system in the presence of an inhomogeneous magnetic field. Using negativity as entanglement measure, we give the dependence of entanglement on each parameter in detail. The result shows that one can get appropriate entanglement by adjusting the magnetic field, Dzyaloshinskii-Moriya interaction and anisotropy parameter simultaneously. 相似文献
7.
Magnetization of anisotropic quantum dots in the presence of the Rashba spin–orbit interaction has been studied for three and four interacting electrons in the dot for non-zero values of the applied magnetic field. We observe unique behaviors of magnetization that are direct reflections of the anisotropy and the spin–orbit interaction parameters independently or concurrently. In particular, there are saw-tooth structures in the magnetic field dependence of the magnetization, as caused by the electron–electron interaction, that are strongly modified in the presence of large anisotropy and high strength of the spin–orbit interactions. We also report the temperature dependence of magnetization that indicates the temperature beyond which these structures due to the interactions disappear. Additionally, we found the emergence of a weak sawtooth structure in magnetization for three electrons in the high anisotropy and large spin–orbit interaction limit that was explained as a result of merging of two low-energy curves when the level spacings evolve with increasing values of the anisotropy and the spin–orbit interaction strength. 相似文献
8.
LIHai-Jin TAORul-Bao 《理论物理通讯》2002,37(5):627-630
Based on a classical Heisenberg lattice model with dipole interaction and the method of spin dynamic simulation,the magnetic configurations (MC),hysteresis loop (HL) and magnetic resistance (MR) of the nanomagnets with different geometries,such as circle,square and rectangle,are studied for different directions of applied field.In the case of perpendicular field to the plane,the magnetization and MR are reversible and have not hysteresis.When the field is applied in the plane,the HL is irreversible and is qualitatively well agreeable with the current experimental results.The MR loop is also irreversible and appears two peaks distributed at two sides around zero field.The peaks of magnetic resistance are relative to the vortex state of similar configuration.Large easy-axis anisotropy will suppress the MC anisotropy,and the large magnetoresistance effect disappears. 相似文献
9.
Angular anisotropy of the alpha emission from241Am nuclei oriented by magnetic hyperfine interaction
Angular anisotropy of the alpha emission from241Am nuclei oriented by magnetic hyperfine interaction at low temperatures in ZrFe2-host have been observed. The sign of the anisotropy indicates unambiguously the enhanced alpha emission from the poles of241Am nucleus. The value of magnetic hyperfine field on241Am nuclei have been estimated from the temperature dependence of the anisotropy. 相似文献
10.
在带有垂直各向异性的二维三角晶格磁体中,当同时存在最近邻铁磁性和第三近邻反铁磁性交换作用时,垂直于膜面施加外磁场会使体系内自旋沿着非共面的方向排列,甚至出现拓扑稳定的斯格明子自旋结构.基于蒙特卡罗模拟方法,本文研究了在该二维阻挫磁体中,竞争性交换作用和外磁场对斯格明子直径的影响.与常规非中心对称的手性磁体中的斯格明子性质类似,外磁场会磁化斯格明子外围自旋而减小斯格明子直径.但是,磁体中反铁磁性交换作用的增强会整体压缩斯格明子.本文结合自旋波理论和蒙特卡罗模拟,首次量化了此类阻挫磁体中斯格明子的直径.结果表明:在弱的反铁磁性交换作用磁体中,斯格明子直径随磁场增大而快速线性减小;随着反铁磁性交换作用的增大,斯格明子直径随外磁场增大的减小变得相对平缓,但在强磁场下也会造成斯格明子直径的加速减小;随着反铁磁性交换作用的增强,斯格明子在不同外磁场下的直径的最大值和中值均从逐渐减小到渐趋稳定,而直径的最小值则从快速减小到表现出很大的涨落.这些现象都可以通过分析斯格明子在不同交换作用和外磁场下的构型和磁能变化加以解释.该项工作阐明了在中心对称的阻挫磁体中斯格明子直径的可调节性,不仅完善了我们对斯格明子本身物理机理的认识,同时也为发展基于斯格明子的新一代存储和逻辑器件提供了理论支撑. 相似文献
11.
The out-of-plane hysteresis loops of small arrays of magnetic
nanoparticles, under the influence of an external field applied
perpendicular to the array and the dipolar interaction are
investigated. The particles are assumed to have a perpendicular
anisotropy energy that tends to align the magnetic moments to be
perpendicular to the array. The magnetization is found to exhibit
a plateaux-and-jumps structure as the external field is swept up
and down. These jumps are associated with jumps in the energy of
the system, and correspond to transition from one configuration of
the moment orientation to another. The energy of different
configurations of the magnetic moments for a 3×3 array in
the limit of weak dipolar interaction is analyzed, as a means to
understand the hysteresis loop. These jumps are more pronounced
in arrays of smaller sizes and when the dipolar interaction is
weak. The configuration of magnetic moments at zero external field
as the field is swept up and down is found to be highly sensitive
to the dipolar interaction. 相似文献
12.
Hamid Arian Zad 《中国物理 B》2016,25(3):30303-030303
In the present work, we initially verify anisotropy effect on the heat capacity of a mixed-three-spin(1/2,1,1/2) system(where spins(1/2,1/2) have XY interaction and spins(1,1/2) have Ising interaction together) at finite temperatures, then,the pairwise entanglement for spins(1/2,1/2), by means of negativity(as a measure of entanglement) as a function of the temperature T, homogeneous magnetic field B, and anisotropy parameter γ is investigated. In addition, we show that one can find magnetic phase transition points for the spins(1/2,1/2) at finite temperatures and understand properly their behavior with respect to the magnetic field and the anisotropy parameter, via the negativity function. An interval of the magnetic field from the negativity diagram of the spins(1/2,1/2) is presented in which quantum phase transition occurs for the tripartite mixed-three-spin system. Finally, some new interesting entanglement witnesses are introduced by using non-degenerate perturbation theory for the mixed-three-spin system. 相似文献
13.
Anatoly A. Ivanov Vitaly A. Orlov 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(3):40
The magnetic structure of a polycrystalline nanowire at the weak or missing magnetostatic interaction exhibits the special self-organization of magnetization. As is known, the magnetization structure forming in a random crystallographic anisotropy field has a characteristic length range, which involves tens and hundreds of crystallites. This leads to the occurrence of stochastic domains. The induced uniform anisotropy of magnetostatic nature or the texture co-directed with the crystallite anisotropy axes masks the picture of stochastic domains. Nevertheless, as we show, the information on stochastic domains remains in the magnetization structure. The experimental techniques for obtaining information on the magnetic properties of stochastic domains are proposed. 相似文献
14.
15.
The equilibrium orientations of magnetic moments that correspond to various values and directions of the biasing field are
found in a set of magnetic films with cubic crystalline anisotropy and uniaxial induced anisotropy. The films are coupled
by exchange interaction of the antiferromagnetic type. Field intervals are established where noncollinear and bistability
states causing orientational phase transitions and hysteresis exist. Ninety degree magnetization switching (per switching
cycle) of the magnetic moments of the films, as well as an orientational phase transition of bifurcation character, is discovered.
Hysteresis loops for 180° in-plane magnetization switching are constructed. 相似文献
16.
We study long wavelength magnetic excitations in lightly doped La2-xSrxCuO4 (x=0.03) detwinned crystals. The lowest energy magnetic anisotropy induced gap can be understood in terms of the antisymmetric spin interaction inside the antiferromagnetic (AF) phase. The second magnetic resonance, analyzed in terms of in-plane spin anisotropy, shows unconventional behavior within the AF state; it led to the discovery of collective spin excitations pertaining to a field induced magnetically ordered state. This state persists in a 9 T field to more than 100 K above the Néel temperature in x=0.01. 相似文献
17.
M. R. Poppinger 《Zeitschrift für Physik B Condensed Matter》1977,27(1):61-68
In this first of two papers we investigate the temperature effect on the spin wave energy and the two-magnon Raman scattering cross section for an antiferromagnet with rutile structure in the spin wave scheme. In the Heisenberg hamiltonian we consider the exchange interaction between magnetic neighbors up to the third order, an effective anisotropy field, and an external magnetic field. In the effective Raman hamiltonian an anisotropy factor, allowed by the crystal symmetry, is taken into account.The theory employs a Green's function method, where the Green's functions are obtained from equations of motion. The results are similar to published ones obtained with diagrammatic techniques.Extract from thesis, Munich, 1974 相似文献
18.
The origin of XY magnetic anisotropy observed in antiferromagnet C6Eu is studied theoretically. A new mechanism of magnetic anisotropy due to the combined action of the π-f exchange and the spin-orbit interaction is proposed. It is shown that this mechanism overcomes the ordinary mechanism due to the crystal field in the case of a Eu2+ ion. 相似文献
19.
The interaction of stray fields and the eddy currents inherent in a sandwich domain structure is studied. This interaction allows us to control the existence of a sandwich domain structure in an amorphous ribbon. The formation of non-uniform magnetic anisotropy in an amorphous ribbon as a result of its annealing in a helical magnetic field is also investigated. 相似文献
20.
Precession of magnetization induced by pulsed optical excitation is observed in a ferromagnetic semiconductor (Ga,Mn)As by time-resolved magneto-optical measurements. It appears as complicated oscillations of a polarization plane of linearly polarized probe pulses, but is reproduced by gyromagnetic theory incorporating an impulsive change in an effective magnetic field due to a change in the magnetic anisotropy. The shape of the impulse suggests a significant nonthermal contribution of photogenerated carriers to the change in anisotropy through spin-orbit interaction. 相似文献