Epitaxial Growth of (111) TbFe₂ by Sputter Deposition

Abstract

The effect of in-plane strain in (111)-oriented epitaxial TbFe₂ films on the magnetization orientations was studied. Magnetocrystalline anisotropy, shape anisotropy, and magnetoelastic energy were calculated to determine the magnetization orientation in the presence of various in-plane strains. Theoretical considerations indicate that a compressive strain smaller than -0.065% can induce an out-of-plane magnetization. DC magnetron sputtering from Tb and Fe elemental targets was used to grow 50, 100, 200, and 400 Å thick epitaxial TbFe₂(111) films at 600°C on (110)-oriented sapphire substrates with 1000 Å thick epitaxial Mo(110) buffer layers. The growth rate of the TbFe₂(111) films was 1.44 Å/sec. X-ray diffractometry, Rutherford backscattering spectrometry, and vibrating sample magnetometry were used to characterize the crystal structure, epitaxial orientation, composition, stress and strain state, and magnetic properties of the TbFe₂ films. The TbFe₂(111) films were epitaxial with twins rotated by 60° and were in tensile strain states with the resulting in-plane magnetization.