Magnetization processes and magnetostriction of Tb0.27Dy0.73Fe2 single crystal along 〈110〉 direction

Abstract

The magnetostriction and magnetization process of a twin-free Tb0.27Dy0.73Fe2 single crystal along the 〈110〉 direction has been studied by strain gauge, vibrating sample magnetometer, and domain observation techniques. It was observed that the magnetostriction of the sample remained unchanged with increasing magnetic fields when H<1 kOe and quickly increased in the range 1<H<7.5 kOe. No “jump” effect was observed during the magnetization process and the magnetostrictive hysteresis was large when H<2.5 kOe. Observations by the Bitter colloid technique at room temperature revealed curved domain walls which became straight at higher and lower temperatures in {100} and {111}, respectively, indicating the transition to different 180° walls for H<1 kOe. The domain patterns were clearest on a {100} surface. Above the spin reorientation temperature, 109° and 71° wall motions dominated the magnetization process in the range 1.5 kOe<H<4 kOe, but below it, clear 90° wall motions were observed. Little change in the magnetized domain pattern was observed at different temperatures suggesting that many domain walls occupy the same planes. Similar room temperature patterns were observed at remanence with an applied stress along 〈111〉 in excess of 5 MPa. These results are consistent with theoretical magnetomechanical behavior based on a 〈1uu〉, 0<u<1, transition in easy direction.