First principles study on the intrinsic resistivity of rectangular Ti2B2 and Mo2B2

In the framework of semiclassical Boltzmann transport theory and by first principles calculations, we study the intrinsic resistivity (arising from the electron-phonon scattering) of two MBene materials: ${\mathrm{Ti}}₂{\mathrm{B}}₂$ and ${\mathrm{Mo}}₂{\mathrm{B}}₂$. We find that the two kinds of MBenes are two-dimensional (2D) good conductors, with lower resistivity than other typical two-dimensional metals. For example, their intrinsic resistivity at room temperature is both significantly lower than the high-buckled plumbene and 2D ${\text{Ti}}₃{\text{C}}₂$, noting that the latter possesses the maximal conductivity among MXene metals accessible so far. The impressive low resistivity of the two MBenes can be attributed to their sizable Fermi surface and relatively weaker electron-phonon (el-ph) interaction. What is more, we find the temperature dependence of the intrinsic resistivity of the two MBenes, i.e., the $\ensuremath{\rho}\text{\ensuremath{-}}T$ relation, disagrees with the prediction of conventional Bloch-Gr\"uneisen theory in both the low and high temperature limits. On one hand, the nontrivial umklapp scattering causes a notable deviation of the $\ensuremath{\rho}\text{\ensuremath{-}}T$ relation of the two MBenes from the ${T}⁴$ law, a general decay rate of 2D metals in the low temperature limit. On the other hand, on the high temperature side, the temperature dependence of the el-ph interaction's spectral function must be taken into account for describing correctly the $\ensuremath{\rho}\text{\ensuremath{-}}T$ relation of actual materials with a sharply varying density of states of electrons around Fermi surfaces such as the case of the two MBenes, though it was often ignored in the relevant literature.