Ab-Initio Calculations on Thermal Strain-Induced Dimerized Phase in Monolayer IrTe₂

Two-dimensional materials are sensitive to external strain and may undergo strain-induced phase transitions depending on thickness. In particular, IrTe₂ has been shown to exhibit superconducting properties at nanometer-scale thickness [1]. However, as the thickness of IrTe₂ decreases further, it becomes susceptible to thermal strain from the substrate. Studies on monolayer IrTe₂ have shown that various phases appear depending on the types of substrates with respective thermal strain properties [2,3]. To see the intrinsic strain properties of monolayer IrTe₂ induced by thermal effect, firstly we study the stability of the phase transitions from electronic and phononic perspectives. In addition, we calculate the thermal expansion coefficient of monolayer IrTe₂. Our calculations show that pristine monolayer IrTe₂ tends to take on a dimerized phase at temperature ~ 630 K and strain , which is not observed in bulk IrTe₂. This finding suggests a possibility of engineering the phase transition of two-dimensional materials using the thermal strain with suitable substrates and of designing desired functionality of two-dimensional materials.<br/><br/><br/>References<br/>[1] S. Park et al., Nat Commun 12, 3157 (2021).<br/>[2] J. Hwang et al., Nat Commun 13, 906 (2022).<br/>[3] H. K. Kim et al., Phys. Rev. B 107, 045112 (2023).