Domain configurations in the giant magnetostrictive Tb x Ho1-x Fe1.9 system in different easy axis regimes

Domains have been observed in Tb x Ho1-x Fe1.9 over the composition range 0<x<0.2 and temperature range -10 to +100 °C, as a function of bias field. In the region where this system is <100> easy, the movement of {110} 90° domain walls is shown to be responsible for the generation of negative magnetostrain, with increasing bias field. When <111> is easy, 71° domain walls in {110} have been identified with a bias field applied. For x=0.1, at remanence, 180° domain walls rotate smoothly with increasing temperature, from {100} when <100> is easy to {110} when <111> is easy. The presence of a bias field, at any temperature, brings out {110} walls which are 90° walls in the <100> easy, low temperature, regime and 71° walls in the <111> easy, high temperature, regime. At intermediate temperatures these walls remain in {110} with the magnetization in directions between <100> and <111>. These domain observations are shown to be consistent with theoretical magnetomechanical behavior based on a <1uu>, 0<u<1, transition in easy axis.