Study on hysteresis characteristics of magnetic domain rotation in Tb0.3Dy0.7Fe2 alloy

Abstract

In this paper, the rotation effects of magnetic domain with different pre-compressive stress and basic magnetic field in the Tb0.3Dy0.7Fe2 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 TbDyFe 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.