Thickness-dependent magnetotransport in ultrathin manganite films

To understand the near-interface magnetism in manganites, ultrathin films of ${\mathrm{La}}_{\mathrm{0.67}}{\mathrm{Sr}}_{\mathrm{0.33}}{\mathrm{MnO}}_{\mathrm{3}}$ were grown epitaxially on single-crystal (001) ${\mathrm{LaAlO}}_{\mathrm{3}}$ and (110) ${\mathrm{NdGaO}}_{\mathrm{3}}$ substrates. The temperature and magnetic field-dependent film resistance is used to probe the film’s structural and magnetic properties. A surface and/or interface related dead layer is inferred from the thickness-dependent resistance and magnetoresistance. The total thickness of the dead layer is estimated to be ∼30 Å for films on ${\mathrm{NdGaO}}_{\mathrm{3}}$ and ∼50 Å for films on ${\mathrm{LaAlO}}_{\mathrm{3}}.$