Magnetostriction-jump effect in〈110〉 oriented Tb0.3Dy0.7Fe1.95 crystal after non-coaxial field annealing

Abstract

An〈110〉 oriented Tb0.3Dy0.7Fe1.95 rod was annealed under a field of 0.3 T, which was applied 35° away from its axis. Magnetostriction-jump effect of the magnetically annealed crystal was investigated under a series of uniaxial compressive pre-stresses ranging from 0 to 30 MPa. The magnetically annealed crystal possessed much higher saturation magnetostriction λs than the ones without applying any pre-stresses. When the compressive pre-stress was less than 20 MPa, the magnetically annealed specimen still exhibited obvious magnetostriction jump effect, possessing improved saturation magnetostriction λs and enhanced burst magnetostriction λm. A satisfactory magnetostriction as high as 2315×10-6 could be obtained in the annealed crystal with the application of a pre-stress of 20 MPa. Furthermore, under a compressive pre-stress below 5 MPa, the critical field at which the magnetostriction-jump effect occurs also decreased, which was beneficial for low field applications. Difference in the magnetization processes caused by magnetic annealing was revealed through investigating the pre-stress dependences of the burst field Hjump and the distribution width of non-180° domain wall motion. Magnetic force microscopy images showed the changes of magnetic domain configurations induced by field annealing. Effects of the induced additional anisotropy on the magnetostrictive behaviors were also discussed.