LATTICE DISTORTIONS OF V2O3 THIN FILMS DURING METAL-TO-INSULATOR TRANSITION

Abstract

ABSTRACT As a prototypical Mott-Hubbard system, bulk vanadium sesquioxide (V2O3), undergoes a first-order Metal-to-Insulator Transition (MIT) from the paramagnetic metallic phase to an antiferromagnetic insulator phase upon cooling to ~160K. Along with MIT, a structural phase transition from rhombohedral to monoclinic structure happens around the same temperature. In the past few decades, the transition temperature of V2O3 has been successfully modified by tens of degrees by introducing lattice strain (through doping, heteroepitaxial growth, etc.). However, how the lattice strain affects the structural distortion and MIT remains elusive to this day. In this work, we studied the lattice distortion of V2O3 thin films heteroepitaxially grown on variously oriented sapphire substrates through X-ray diffraction at Cornell High Energy Synchrotron Source (CHESS). We show that the in-plane biaxial strain drastically affects the intrinsic lattice distortions and the microstrain states in films. Besides, an intermediate interfacial structure was observed in the film grown on (100)-oriented substrate, which is a plausible model for explaining the recent discovery of a memory effect in electrical transport properties of V2O3.