Influence of chemical composition and crystallographic orientation on the interfacial magnetism in BiFeO3/La1−xSrxMnO3 superlattices

Abstract

The emergence of magnetism unique to the interface between the multiferroic BiFeO3 (BFO) and ferromagnetic La1−xSrxMnO3 (LSMO) offers an opportunity to control magnetism in nanoscale heterostructures with electric fields. In this paper, we investigate the influence of chemical composition and crystallographic orientation on the interfacial magnetism of BFO/LSMO superlattices. Our results reveal that the induced net magnetic moment in the BFO layers increases monotonically with increasing saturation magnetization of the LSMO layers. For the (100)-BFO/LSMO (x=0.2) superlattice, the induced moment reaches a record high value of ∼2.8μB/Fe. No interfacial magnetization is observed at the (100)-BFO/LSMO interface when LSMO is an antiferromagnet. In contrast to (100)-oriented superlattices, no induced moment is observed in (111)-BFO layers. Our results suggest the interfacial structural reconstruction may not be a sufficient condition for the enhanced net moment in BFO layer. Instead, spin canting induced by interfacial exchange coupling is proposed in the (100)- but not in the (111)-BFO, leading to the large net magnetization at the (100)-oriented interface. This work further demonstrates the importance of exchange coupling across heterointerfaces for spin canting in nominally antiferromagnets, providing a pathway to control the magnetic properties of artificial oxide heterostructures.