Emergent ferromagnetism in layered VCrO3 corundums

In this proposal, we want to identify and understand interfacial magnetism that emerges in a layered ilmenite VCrO3 thin film. High-quality VCrO3 superlattices (SLs) involving the alternation of several monolayers of V2O3 and Cr2O3 have been grown by oxygen-assisted molecular beam epitaxy. The layered structure with atomically sharp interfaces has been confirmed by X-ray reflectivity and HAADF-STEM. Furthermore, the ilmenite (1ML periodic limit SL) has shown the emergence of a weak FM ordering, as also confirmed by first-principle calculations. The aim is to identify the interfacial nature of this FM ordering by studying a series of SLs with increasing periodicity, and to understand the fundamental exchange mechanism.

在本研究提案中，我们旨在识别并理解层状钛铁矿型(ilmenite) VCrO₃薄膜中出现的界面磁性。我们通过氧辅助分子束外延(oxygen-assisted molecular beam epitaxy)成功制备了高质量的VCrO₃超晶格(SLs)，该超晶格由V₂O₃与Cr₂O₃的若干单原子层交替堆叠而成。借助X射线反射法(X-ray reflectivity)与高角环形暗场扫描透射电子显微镜(HAADF-STEM)，已证实该结构具备原子级清晰的界面与层状排布特征。此外，钛铁矿型1单原子层周期极限超晶格样品展现出弱铁磁有序(FM ordering)，该结果亦通过第一性原理计算(first-principle calculations)得到验证。本研究的目标为：通过分析一系列周期递增的超晶格样品，明确该铁磁有序的界面本质，并阐明其核心交换机制。