Enhanced Ferromagnetism in Atomically Thin Oxides Achieved by Interfacial Reconstruction
Discoveries of ferromagnetic materials with ultrathin thickness are of great importance for both fundamental science and technological applications. Transition metal oxides (TMOs) provide promising candidates in the context of next‐generation spintronics, despite the severe decay of ferromagnetism as the thickness reduces to the nanometer regime. Here, in this work, an efficient strategy to eliminate the magnetic dead layer in atomically thin oxides is presented, by using the epitaxial interface of 3 d and 5 d oxide monolayers that reconciles both strong exchange interaction and large uniaxial magnetic anisotropy. Combining multiple experimental methods, a ferromagnetic transition in an ultrathin oxide heterostructure comprised of only one La 0.2 Sr 0.8 MnO 3 monolayer sandwiched by SrIrO 3 monolayer (total thickness of three unit‐cells) is unambiguously demonstrated. Remarkably, a largely enhanced saturation magnetization (2 µ B Mn −1 ) and Curie temperature (80 K) are observed for the single manganite monolayer, as compared to previously reported ferromagnetic monolayer oxides. The results demonstrate a general strategy for creating robust ferromagnetism in ultrathin TMOs, potentially enabling novel oxide spin‐orbitronic devices.