Role of doped Ru in coercivity-enhanced La${}_{0.6}$Sr${}_{0.4}MnO$_3$ thin film studied by x-ray magnetic circular dichroism

Abstract

The coercivity of La${}_{1-x}$Sr${}_x$MnO${}_3$ thin films can be enhanced by Ru substitution for Mn. In order to elucidate its mechanism, we performed soft x-ray absorption and magnetic circular dichroism measurements at the Ru M${}_{2,3}$ and Mn L${}_{2,3}$ edges. We found that the spin direction of Ru and Mn are opposite and that Ru has a finite orbital magnetic moment. Cluster-model analysis indicated that the finite orbital magnetic moment as well as the reduced spin moment of Ru result from local lattice distortion caused by epitaxial strain from the SrTiO${}_3$ substrate in the presence of spin-orbit interaction.

10 pages, 4 figures, 2 tables, accepted Applied Physics Letters