The carrier mobility and superconducting properties of monolayer oxygen-terminated functionalized MXene Ti₂CO₂

Abstract

In this study, the carrier mobility of monolayer Ti₂CO₂ was evaluated by employing the Boltzmann transport equation and superconducting transition temperature (Tc) of Ti₂CO₂ was determined by utilizing the Migdal and Eliashberg formalism in the first-principles framework. In contrast to previous studies, the results reveal that optical phonons in monolayer Ti₂CO₂ have dominant roles in scattering processes, which significantly reduce the mobility of carriers. Alongside the rigid band model, the jellium model is implemented to investigate the screening effects on electron-phonon interactions. Based on the jellium model and full-band electron-phonon calculations, the predicted maximum electron mobility at room temperature is 38 cm²V⁻¹s⁻¹ in which 80% of the total scattering rate originates from the intra-valley transitions within the M-valleys, indicating the crucial role of the long wavelength phonon wavevectors in scattering processes. On the other hand, for the p-type material, a maximum room temperature mobility of about 285 cm²V⁻¹s⁻¹ is calculated, which can be explained by a relatively small effective mass and tiny scattering phase space. Moreover, a maximum Tc of 39 (10) K is obtained for the n-type monolayer Ti₂CO₂ based on the rigid (jellium) model. Outcomes indicate that the important peaks of α²F(ω) are mainly caused by the optical phonons. The remarkable couplings between the electron states and phonons are related to the non-zero slope of (near the Brillouin zone center) the longitudinal optical branch denoted by Eu caused by the displacements of oxygen and carbon atoms at intermediate and high energy ranges of phonon dispersion, respectively.