Linear Interplay Between Raman Shift and Laser Irradiation in Photothermal‐Strained Monoclinic Vanadium Dioxide

Abstract Vanadium dioxide as a strongly correlated electron material undergoes metal‐insulator phase transitions and ferroelastic domain switching which highly couple to local strain distribution. Understanding the mechanisms and achieving the modulations require precise and high‐resolution characterization of strain in vanadium dioxide. Micro‐Raman spectroscopy is widely used to nondestructively characterize the strain on the surface of materials. However, vanadium dioxide is sensitive to multi‐fields and with multiple physical properties correlated. It is vital and challenging to uncouple the multiple responses of vanadium dioxide to micro‐Raman spectroscopy and achieve precise characterization of strain distribution. Herein, a linear relation between Raman shift and laser irradiation is revealed, which is originated from photothermal strain in monoclinic vanadium dioxide. By linear fitting and extrapolation, the strain‐dependent coefficient is obtained for drifting of Raman shift and the intrinsic Raman shift without strain or laser irradiation, which enables to precisely characterize the strain distribution in vanadium dioxide.