Tb0.3Dy0.7Fe2单晶中巨磁致伸缩的逆效应

研究了Terfenol-D材料中巨磁致伸缩的逆效应，即磁机械效应.基于Stoner-Wohlfarth(SW)模型，考虑磁晶各向异性和应力各向异性能，依据自由能极小原理，获得了退磁态下Terfenol-D单晶中磁化强度方向和压应力的关系.采用数值方法求解了平衡条件下的非线性方程组.理论结果表明，Terfenol-D巨磁致伸缩单晶中的磁各向异性取决于磁晶各向异性和应力各向异性之间的竞争.在压应力的作用下，Terfenol-D单晶中的磁各向异性由立方向单轴转变.理论和实验结果的比较表明，存在一个临界压应力，使磁致伸缩效应达到极大值.该理论结果还解释了压应力使得Terfenol-D单晶材料难于磁化和磁致伸缩效应出现极大值的实验事实.理论计算不仅为研究这类问题提供了一个更准确的方法，而且其结果也有助于理解类似材料中的磁化过程. 关键词： Terfenol-D 磁机械效应 巨磁致伸缩效应 磁各向异性

The inverse magnetostrictive effect in Tb_(0.3)Dy_(0.7)Fe_2

The inverse magnetostrictive effect, also called magnetomechanical effect, in Terfenol-D material, has been investigated in this paper. Based on Stoner-Wohlfarth (SW) model, taking into account magnetocrystalline and stress-induced anisotropy energy, and following the free energy minimization procedure, direction cosines of magnetization in Terfenol-D single crystal in demagnetized state have been obtained as a function of the compressive stress. The nonlinear equations for equilibrium have been solved numerically. The results indicated that under compressive stress, magnetic anisotropy in Terfenol-D is determined by a competition between magnetocrystalline and stress-induced anisotropy energy, and changes from cubic symmetry to uniaxial. A comparison between experimental and numerical results showed that there is a maximum magnetostriction in Terfenol-D at a certain stress. According to our numerical results, experimental observations that compressive stress makes Terfenol-D hard to be magnetized and leads to the maximum magnetostriction can be explained. The computation in this paper presents a more accurate approach to similar investigations, and its numerical results would be helpful for a better understanding of magnetization process of similar materials.