Tb0.3Dy0.7Fe2合金磁畴偏转的滞回特性研究

Study on hysteresis characteristics of magnetic domain rotation in Tb_(0.3)Dy_(0.7)Fe_2 alloy

研究了不同载荷作用下Tb_(0.3)Dy_(0.7)Fe_2合金在压磁和磁弹性效应中磁畴偏转的滞回特性.基于StonerWolhfarth模型的能量极小原理,采用绘制自由能-磁畴偏转角度关系曲线的求解方法,研究了压磁和磁弹性效应中载荷作用下的磁畴角度偏转和磁化过程,计算分析了不同载荷作用下磁畴偏转的滞回特性.研究表明,压磁和磁弹性效应中磁畴偏转均存在明显的滞回、跃迁效应,其中磁化强度的滞回效应来源于磁畴偏转的角度跃迁;压磁效应中预加磁场的施加将增大磁化强度的滞回,同时使滞回曲线向大压应力方向偏移;磁弹性效应中磁畴偏转的滞回存在两个临界磁场强度,不同磁场强度下合金具有不同的磁畴偏转路径和磁化滞回曲线,临界磁场强度的大小取决于预压应力的施加.理论分析对类磁致伸缩材料磁畴偏转模型的完善和材料器件的设计应用非常有意义.

In this paper, the rotation effects of magnetic domain with different pre-compressive stress and basic magnetic field in the Tb_（0.3）Dy_（0.7）Fe_2 alloy have been studied, the curves of magnetization induced by the rotation of magnetic domains are calculated, and the hysteresis characteristics of magnetization in the process of piezomagnetic and magnetoelastic effects are summarized. Based on the minimal value principle of three-dimensional Stoner-Wolhfarth（S-W） model, the total free energy of magnetostrictive particles（including magneto-crystal line anisotropy energy, stress-induced anisotropy energy, and magnetic field energy） is calculated, the curve of free energy is plotted as a function of domain rotation angle for various compressive stresses and magnetic fields. Then, the values of rotation angle for the magnetic domains in the eight easy axial directions {111} are given, and the summation values of magnetization induced by the rotations of magnetic domain angle are analyzed, the hysteresis characteristics and the hysteresis loops of magnetic domain rotations are calculated and discussed. All the above results indicate that the rotations of magnetic domains in the Tb Dy Fe alloy have hysteresis and transition effects in its piezomagnetic and magnetoelastic processes, and the hysteresis effect of magnetization is always induced by the irreversible transitions of domain angle rotation. Due to the load of magnetic field and compressive stress, the angle of the eight easy axial domains {111} will rotate to the more suitable free energy directions, the reversible and irreversible transitions of domain rotation appear in this rotation, and irreversible transition will induce a larger value of changes in the magnetization existing as a hysteresis loop. Also, in the piezomagnetic effect,magnetization hysteresis loop appears with the load of basic magnetic field, and the increase of magnetic field will help to enhance its hysteresis loop and lead to the hysteresis curve deflected toward the greater compressive stress direction. Thirdly, the hysteresis effects of magnetic domain rotation have two important critical magnetic fields in the magnetoelastic process： the magnetostrictive materials will have different domain rotation paths and hysteresis curve in different basic magnetic fields, and the value of critical field will be influenced by the load of pre-compressive stress.Lastly, the experimental testing is used to verify the model and calculations, and the test results of magnetic remanence are in good agreement with the calculated results, especially in the larger values of pre-compressive stress loads. The above computations have a significance for perfecting magnetic domain deflection model and the results are helpful for designing and analyzing of magnetosrictive materials in application.