Anisotropic metal–insulator transition in strained VO2(B) single crystal

Abstract

Mechanical strain can induce noteworthy structural and electronic changes in vanadium dioxide, imparting substantial scientific importance to both the exploration of phase transitions and the development of potential technological applications. Unlike the traditional rutile (R) phase, bronze-phase vanadium dioxide [VO2(B)] exhibits an in-plane anisotropic structure. When subjected to stretching along distinct crystallographic axes, VO2(B) may further manifest the axial dependence in lattice–electron interactions, which is beneficial for gaining insights into the anisotropy of electronic transport. Here, we report an anisotropic room-temperature metal–insulator transition in single-crystal VO2(B) by applying in-situ uniaxial tensile strain. This material exhibits significantly different electromechanical responses along two anisotropic axes. We reveal that such an anisotropic electromechanical response mainly arises from the preferential arrangement of a strain-induced unidirectional stripe state in the conductive channel. This insulating stripe state could be attributed to the in-plane dimerization within the distorted zigzag chains of vanadium atoms, evidenced by strain-modulated Raman spectra. Our work may open up a promising avenue for exploiting the anisotropy of metal–insulator transition in vanadium dioxide for potential technological applications.