Phase stabilization of strained 1T monolayer IrTe2 by electron-phonon coupling modulationtest
Two-dimensional 1T monolayer (ML) IrTe2 exhibits complex structural phase transitions under external stimuli like temperature or strain. While various mechanisms have been suggested as a major driving force for rich structural phases, their true origin is not comprehensively understood. In this study, we investigate the strain-induced phase transition in ML IrTe2 using first-principles calculations and constrained density-functional perturbation theory. We find that the soft phonons associated with structural instability are hardened by biaxial tensile strain and that the trigonal phase is stabilized. We show that sharp peaks in the bare electronic susceptibility due to the Fermi surface nesting persists even under the biaxial strain and that the renormalization of phonon self-energy is affected mostly by the interaction of phonons with electrons in low-energy bands crossing the Fermi level. We find that the off-diagonal matrix elements of the phonon self-energy is sensitive to the biaxial tensile strains, contributing to the stabilization of the soft phonon modes.