Crystal orientation dependence of magnetostriction of twinned perovskite cobalt oxide

Highlights: • Crystal orientation dependence of magnetostriction was studied. • The magnetostriction along ${\left[111\right]}_{\text{c}}$ and ${\left[110\right]}_{\text{c}}$ showed hysteresis and residual strains. • Hysteresis and residual strain were not observed along ${\left[001\right]}_{\text{c}}$. • The rearrangement of the domains qualitatively accounts for the magnetostrictions. We investigated crystalline orientation dependence of magnetostriction of twinned rhombohedral perovskite cobalt oxide, La_0.8Sr_0.2CoO₃. The magnetostriction in a magnetic field applied along the pseudo-cubic ${\left[111\right]}_{\text{c}}$ and ${\left[110\right]}_{\text{c}}$ axes showed large hysteresis and residual strains. On the other hand, hysteresis and residual strain were not observed in the applied magnetic field along the ${\left[001\right]}_{\text{c}}$ axis. The large hysteresis and residual strains of the magnetostriction along the ${\left[111\right]}_{\text{c}}$ and ${\left[110\right]}_{\text{c}}$ axes are successfully interpreted as a rearrangement of the rhombohedral domains with the magnetocrystalline hard axis along the rhombohedral ${\left[111\right]}_{\text{r}}$. The no hysteresis and no residual strain of the magnetostriction along the [001]c axis are interpreted by equal projection to [001]c axis of [111]r of all the domains. The twinned structure of La_0.8Sr_0.2CoO₃ with the magnetic anisotropy qualitatively accounts for the crystalline-orientation dependence of the magnetostrictions.