Magnetic and electronic structure of ultrathinLa1−xSrxMnO3films at half doping

Abstract

The magnetic, transport, and electronic properties of ultrathin epitaxial ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ (LSMO) films at near half doping ($x=0.47$, 0.50, and 0.55), grown under different misfit strains on $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$(001) and ${\mathrm{La}}_{0.18}{\mathrm{Sr}}_{0.82}{\mathrm{Al}}_{0.59}{\mathrm{Ta}}_{0.41}{\mathrm{O}}_{3}$(001) (LSAT) substrates, are investigated. We find that all films exhibit metallic behavior below the magnetic critical temperature, while the magnetic properties change markedly with both doping and strain. However, while increased doping favors antiferromagnetic ordering, strain is the driving mechanism for the change in the magnetic properties, where with increasing tensile strain the magnetic ground state changes from ferromagnetic to antiferromagnetic at a critical lattice misfit threshold of about \ensuremath{-}1%. The bulk magnetometry data are confirmed by x-ray magnetic circular dichroism spectroscopy, while x-ray magnetic linear dichroism measured at room temperature demonstrates a progressive change in the orbital occupancy with increasing misfit strain from out of plane to in-plane, leading to a preferred antiferromagnetic metallic state at larger tensile strains.