Electron-phonon interaction in TinO2n−1 using first-principles calculations

Abstract

In the present study, the electronic, phonon, and electron-phonon interactions of titanium suboxide structures including TiO, ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3},$ ${\mathrm{Ti}}_{3}{\mathrm{O}}_{5},$ ${\mathrm{Ti}}_{4}{\mathrm{O}}_{7},$ and ${\mathrm{Ti}}_{5}{\mathrm{O}}_{9}$ were investigated in the framework of density-functional theory. The mechanism of superconductivity in these materials seems to be phonon mediated, probably with participation of paramagnetic spin fluctuations. The influence of pressure on the superconducting transition temperature $({T}_{C})$ of cubic TiO and ${\mathrm{Ti}}_{4}{\mathrm{O}}_{7}$ could be explained by this mechanism. Our calculations predict a low ${T}_{\mathrm{C}}$ of \ensuremath{\sim}3.5 K for ${\mathrm{Ti}}_{5}{\mathrm{O}}_{9}$. It implies that ${\mathrm{Ti}}_{5}{\mathrm{O}}_{9}$ would be a superconductor lying in the weak coupling regime.