共查询到19条相似文献,搜索用时 140 毫秒
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本文研究了Co_xZn-(1-x)(Pe_yCr(1-x)_2O_4尖晶石系统的磁性,测量了不同成份样品的低频弱场交流磁化率与低场直流磁化强度的温度关系。根据实验结果,给出了该系统可能的磁相图。发现在该系统中相当宽的成份范围内,都存在自旋玻璃的重入现象。同时发现,自旋玻璃的重入温度随磁性离子浓度增加而增加。这些行为是磁性离子浓度含量较高和多种磁性离子共存系统的共同特性。还讨论了自旋玻璃重入行为的机制。认为该尖晶石系统中的重入自旋玻璃态,是由亚铁磁长程序解体而形成的大量亚铁磁微畴或自旋团与自旋玻璃共存的状态。 相似文献
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对含有次近邻节点自旋交换耦合的自旋-1/2伊辛-海森伯钻石链体系进行了研究,利用矩阵对角化和传递矩阵方法对基态磁相和宏观热力学量进行了严格求解,重点探讨了所有交换耦合均为反铁磁耦合时,体系节点伊辛自旋间次近邻相互作用的影响.研究结果表明次近邻节点伊辛自旋存在反铁磁耦合时会增强系统的阻挫效应,引入破坏平移对称性的经典亚铁磁相,使基态呈现出上上上下上上的自旋构型以及磁化曲线新颖的2/3磁化平台,丰富了体系的基态相图和宏观磁性行为. 相似文献
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稀磁半导体--自旋和电荷的桥梁 总被引:5,自引:0,他引:5
稀磁半导体可能同时利用载流子的自旋和电荷自由度构造将磁、电集于一体的半导体器件.尤其是铁磁半导体材料的出现带动了半导体自旋电子学的发展.室温铁磁半导体材料的制备,半导体材料中有效的自旋注入,以及自旋在半导体结构中输运和操作已成为目前半导体自旋电子学领域中的热门课题.稀磁半导体呈现出强烈的自旋相关的光学性质和输运性质,这些效应为人们制备半导体自旋电子学器件提供了物理基础. 相似文献
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利用不变本征算符法计算了X-Y-Z模型各向异性海森伯亚铁磁系统的自旋波能量,并讨论了此系统特殊情形下的自旋波能量及不变本征算符法的优点与不足. 相似文献
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通过引入描述电荷-磁场和自旋-磁场相互作用竞争关系的自旋因子,研究了磁场和简谐势阱双重约束的二维带电自旋-1/2费米气体的磁性质.结果表明,当自旋因子很小时,系统显示出抗磁性,随着自旋因子的进一步增大,系统逐渐转变为顺磁性.自旋因子的临界值将磁化强度划分为抗磁性区和顺磁性区,临界值随磁场和温度的增大仅发生微小的改变. 相似文献
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We study the existence of dynamic compensation temperatures in the mixed spin-1 and spin-3/2 Ising ferrimagnetic system Hamiltonian with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on a hexagonal lattice. We employ the Glauber transitions rates to construct the mean-field dynamic equations. We investigate the time dependence of an average sublattice magnetizations, the thermal behavior of the dynamic sublattice magnetizations and the total magnetization. From these studies, we find the phases in the system, and characterize the nature (continuous or discontinuous) of transitions as well as obtain the dynamic phase transition (DPT) points and the dynamic compensation temperatures. We also present dynamic phase diagrams, including the compensation temperatures, in the five different planes. A comparison is made with the results of the available mixed spin Ising systems. 相似文献
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S. Chen L. Wang Y. P. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(3):265-270
We study the ground-state properties of frustrated Heisenberg ferrimagnetic
ladders with antiferromagnetic exchange interactions and two types of
alternating sublattice spins. In the limit of strong rung couplings, we show
that the mixed spin-1/2 and spin-1 ladders can be systematically mapped onto
a spin-1/2 Heisenberg model with additional next-nearest-neighbor exchanges.
The system is either in a ferrimagnetic state or in a critical spin-liquid
state depending on the competition between the spin exchanges along the legs
and the diagonal exchanges. 相似文献
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Hadey K. Mohamad 《Journal of magnetism and magnetic materials》2011,323(1):61-66
I studied the ferrimagnetic Ising model with nearest neighbour interactions for a square lattice and simple cubic one, using mean field theory. The free energy of a mixed spin Ising ferrimagnetic model was calculated from a mean field approximation of the Hamiltonian. By minimizing the free energy, I obtained the equilibrium magnetizations and the compensation temperatures. Clear indications of the single-ion anisotropies on the compensation points of the mixed spin-3/2 and spin-5/2 ferrimagnetic lattices are found. Some interesting behaviors of these systems are obtained depending not only on the values of magnetic anisotropies for both sublattice sites but also on the lattice structure. The longitudinal magnetic fields dependence of the spin compensation temperature is the main focus of research. The possibility of many compensation temperatures is indicated. 相似文献
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The magnetization of mixed spin-1/2, 1 Ising diamond chain with antiferromagnetic spin exchange interaction has been investigated by using the Monte Carlo simulation. Magnetization behaviors with different antiferromagnetic interactions are simulated under magnetic field at low temperature. The behaviors are studied in two different cases. In one case the absolute value of the interaction between two spin-1/2 atoms is the largest and in the other case it is not the largest. Multiple plateaus of magnetization M, such as plateaus at M=±1, M=0 and M=±0.566 are obtained. The plateaus at M=±0.566 correspond to two metastable states. The M=0 plateau may disappear at some specific values of spin exchange interactions. The spin configurations were checked when the plateaus appear. The dimmer and trimmer states are found. 相似文献
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The magnetic properties of bond-diluted nearest-neighbor interaction mixed spin-1/2 and spin-1 Ising ferrimagnetic spin system with different transverse fields are investigated within the framework of the finite cluster approximation (FCA). Particular emphasis is given to the square lattice with coordination number 2 = 4 for which magnetizations are obtained. The interactions Jij are assumed to be independent random variable with distribution P(Jij) = pδ(Jij-J) + (1-p)δ(Jij), where J < 0. If bond concentration p varies in the certain ranges, we find that the compensation temperature is obtained for the values of the different transverse fields Ω1/2 and Ω1 in a restricted region. We obtain the values of the critical different transverse fields and critical bond concentration in this paper. 相似文献
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Godoy et al. (Phys. Rev. B 69, 054428, 2004) presented a study of the magnetic properties of a mixed spin (1/2,1), Ising ferrimagnetic model on a hexagonal lattice without
an oscillating magnetic field. They employed dynamic mean-field calculations and Monte Carlo simulations to find the compensation
point of the model and to present the phase diagrams. It has been found that the N-type compensation temperature appears only when the intrasublattice interaction between spins in the σ sublattice is ferromagnetic. Moreover, the system only undergoes a second-order phase transition. In this work, we extend
the study a dynamic compensation temperature of a mixed spin-1/2 and spin-1 Ising ferrimagnetic system on a hexagonal lattice
in the presence of oscillating magnetic field within the framework of dynamic mean-field calculations. We find that the system
displays the N-type compensation temperature. We also calculate dynamic phase diagrams in which contain the paramagnetic, ferrimagnetic,
nonmagnetic fundamental phases and two different mixed phases, depending on the interaction parameters and oscillating magnetic
field. The system also exhibits tricritical and reentrant behaviors. 相似文献
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WEI Guo-Zhu MIAO Hai-Ling 《理论物理通讯》2009,51(4):756-760
The magnetic properties of a mixed spin-3/2 and spin-2 and a mixed spin-3/2and spin-5/2 Ising ferromagnetic system with different anisotropies are studied by means of mean-field theory (MFT). The dependence of the phase diagram on single-ion anisotropy strengths is studied too. In the mixed spin-3/2 and spin-2 Ising model, besides the second-order phase transition, the first order-disorder phase transition and the tricritical line are found. In the mixed spin-3/2 and spin-5/2 Ising model, there is no first-order transition and tricritical line. 相似文献
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The stationary states of the kinetic mixed spin-2 and spin-5/2 Ising ferrimagnetic system with repulsive biquadratic coupling
are examined within a mean-field approach under the presence of a time varying (sinusoidal) magnetic field. We employ Glauber-type
stochastic dynamics to construct a set of coupled mean-field dynamic equations, and we solve these equations to find the phases
in the system. We also investigate the thermal behavior of the dynamic order parameters to characterize the nature (continuous
or discontinuous) of the dynamic phase transitions (DPTs) and obtain the DPT points. The phase diagrams are presented in the
reduced magnetic field amplitude and reduced temperature plane, and a comparison is made with the results of other kinetic
mixed spin systems. We also study the behavior of the dynamic magnetic hysteresis and investigate the effects of the frequency
on hysteresis properties, and we find the results are in good agreement with some previous theoretical and experimental works. 相似文献
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We calculate the dynamic phase transition (DPT) temperatures and present the dynamic phase diagrams in the kinetic mixed spin-1/2 and spin-5/2 Ising model under the presence of a time-dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the set of mean-field dynamic equations. The time variation of the average magnetizations and the thermal behavior of the dynamic magnetizations are investigated, extensively. The nature (continuous or discontinuous) of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. The DPT points are obtained and the phase diagrams are presented in two different planes. Phase diagrams contain four fundamental phases and three coexistence or mixed phases, which strongly depend on interaction parameters. The phase diagrams are discussed and a comparison is made with the results of the other mixed spin Ising systems. 相似文献