Enhancing spin splitting by symmetry and molecular orbital hybridization in VO2

Abstract

In spintronic devices, one of the concerned focuses is spin splitting, which is existing in heavy metal with strong spin–orbit coupling (SOC) and some materials with broken symmetry. Recently, non-relativistic spin splitting originated from symmetric breaking has been proved in materials with low atomic numbers. Herein, based on inherent asymmetric octahedrons in vanadium dioxide (VO2) and the adjustable charge-spin conversion efficiency, we mainly survey non-relativistic spin splitting in VO2 from a symmetric perspective of bulk, interface, and surface, and hybridization of the molecular orbital. The results demonstrate that there is a tiny spin splitting (8.2 meV) in the rutile-like monoclinic (RM) VO2 bulk. Nevertheless, a huge splitting can be realized by modulating the hybridization of molecular orbital by fabricating the interface with different materials. Moreover, when we give priority to VO2(RM)/TiO2 composite layer (164 meV), the results suggest that the splitting can be also manipulated by different interfacial types and increased the number of layers of VO2(RM). This manner of manipulating symmetries of interface and surface and changing the hybridization of molecular orbital sheds light on understanding the electronic structure and acquiring an enhanced splitting of VO2, which provides the possibility of the application of VO2 in spintronic devices.