Depth-Resolved\nProfile of the Interfacial Ferromagnetism\nin CaMnO<sub>3</sub>/CaRuO<sub>3</sub> Superlattices

Emergent magnetic phenomena at interfaces represent a\nfrontier\nin materials science, pivotal for advancing technologies in spintronics\nand magnetic storage. In this Letter, we utilize a suite of advanced\nX-ray spectroscopic and scattering techniques to investigate emergent\ninterfacial ferromagnetism in oxide superlattices composed of antiferromagnetic\nCaMnO<sub>3</sub> and paramagnetic CaRuO<sub>3</sub>. Our findings\ndemonstrate that ferromagnetism exhibits an asymmetric profile and\nmay extend beyond the interfacial layer into multiple unit cells of\nCaMnO<sub>3</sub>. Complementary density functional calculations reveal\nthat the interfacial ferromagnetism is driven by the double exchange\nmechanism, facilitated by charge transfer from Ru to Mn ions. Additionally,\ndefect chemistry, particularly the presence of oxygen vacancies, can\nplay a crucial role in modifying the magnetic moments at the interface,\npossibly leading to the observed asymmetry between the top and bottom\nCaMnO<sub>3</sub> interfacial magnetic layers. Our findings underscore\nthe potential of manipulating interfacial ferromagnetism through point\ndefect engineering.