In-situ studies of magnetostriction in TbxHo1-xFe1.9Mn0.1 Laves compounds

•Direct experimental evidence for EMD is obtained by electron holography technique.•In-situ studies of magnetic domain and magnetostriction by magnetic field-LTEM.•Anisotropy compensation and a high low-field magnetostriction are obtained.•Correlation between magnetic anisotropy, domain wall motion and magnetostriction. The magnetic domain structure and magnetostrictive properties of TbxHo1-xFe1.9Mn0.1compounds have been investigated by in-situ Lorentz transmission electron microscopy (LTEM). The magnetocrystalline anisotropy compensation has been realized to be around x = 0.12 based on the easy magnetization direction (EMD) and by evaluating magnetocrystalline anisotropy constant K1, magnetization and magnetostriction. The EMD at room temperature rotates from the 〈1 0 0〉 axis for x ≤ 0.10 to 〈1 1 1〉 axis for x ≥ 0.12, which is detected directly by electronic holography technique. The magnetic domain wall movements were observed by in-situ magnetic field LTEM, and the critical magnetic field Hcr decreases continuously from 100 Oe for the Tb-rich side of x = 0.16 to 60 Oe for the Tb-poor side of x = 0.12, owing to the decrease in magnetocrystalline anisotropy subjected by anisotropy compensation. A high low-field magnetostriction (λa ~ 200 ppm at 1 kOe) is achieved at the critical magnetocrystalline anisotropy compensation point of x = 0.12. This work helps to understand the correlation between magnetocrystalline anisotropy, magnetization process, magnetic domain wall motion and magnetostriction in the C15 Laves phase system.