Tuning the charge-transfer energy regime and emergent magnetic order in rare-earth nickelate / titanate superlattices

Previous studies have suggested that a large difference in electron affinity can cause interfacial charge transfer from Ti to Ni in LaTiO3/LaNiO3 heterostructures, leading to large orbital polarization, crossover of charge-transfer (CT) energy regimes, and possible magnetic orders not found in bare LaNiO3. Particularly, a preliminary RIXS measurement (resolution: 100 meV) has revealed a possible existence of low-energy magnon excitations at the Ni L2 edge. Here, we propose a systematic study of nLaTiO3/mLaNiO3 superlattices with varying n/m ratios using high-resolution RIXS (resolution: 35 meV) at Ni L2 edge, to resolve these low-energy features and observe their evolution as a function of confinement and CT energy regimes. The results will identify the nature of the possible magnetic order, and its existence would indicate an emergent transformation of LaNiO3 from a paramagnetic metal into a magnetic insulator.