Magnetocrystalline Anisotropy of SrRuO₃

Abstract

Magnetocrystalline anisotropy in SrRuO₃ is measured by a torque magnetometer using a single-crystal sample. It is found that it has a large amount of magnetic anisotropy. (K₁=6.35×10⁶, K₂=(−)10.8₄×10⁶ and K₃=5.33×10⁵ erg/cm³ at 4.2 K.), where the anisotropy energy is expressed as,
E_K=K₁cos²θ+K₂cos⁴θ+K₃sin⁴θcos²φsin²φ.
The a- and b-axes of the crystal are two easy axes of magnetization, but the c-axis is only a stable direction of magnetization in a magnetic field. Torque curves observed (in the (010) and (110) planes) are rather unusual, but are analyzed by a ‘partially rotatable magnetization vector’ model. Temperature variations of K₁, K₂, and K₃ were also investigated. Some possible origins of the large anisotropy in SrRuO₃ are suggested.