Electron-Phonon Scattering in the Presence of Soft Modes and Electron Mobility in SrTiO3 Perovskite from First Principles

Abstract

Structural phase transitions and soft phonon modes pose a longstanding challenge to computing electron-phonon (e-ph) interactions in strongly anharmonic crystals. Here we develop a firstprinciples approach to compute e-ph scattering and charge transport in materials with anharmonic lattice dynamics. Our approach employs renormalized phonons to compute the temperaturedependent e-ph coupling for all phonon modes, including the soft modes associated with ferroelectricity and phase transitions. We show that the electron mobility in cubic SrTiO3 is controlled by scattering with longitudinal optical phonons at room temperature and with ferroelectric soft phonons below 200 K. Our calculations can accurately predict the temperature dependence of the electron mobility in SrTiO3 between 150−300 K, and reveal the microscopic origin of its roughly T −3 trend. Our approach enables first-principles calculations of e-ph interactions and charge transport in broad classes of crystals with phase transitions and strongly anharmonic phonons.

Understanding the lattice thermal conductivity of SrTiO3 from an ab initio perspective

“…The triply degenerate polar mode was previously identified, using other methods, as one of the main sources of phonon-phonon scattering [14,39]. Apart from that, in a recent work, this mode was also reported to be electron-phonon active [40]. Figure 3 shows the lineshape for three different unit cell volumes at 300 K for a cubic structure.…”

High‐Mobility 2D Hole Gas at a SrTiO3 Interface

“…[ 16 ] Meanwhile, may possibly be the value at the Γ point, whose energy is just below that at the M point (the energy difference between the Γ and M points of the top of the valence band is 0.3 eV in the case of bulk STO, [ 31 ] but it may be smaller due to quantum confinement in the 2DHG). In the case of n‐type STO, at the Γ point, strong coupling with phonons, whose strength is seven times stronger than at the M point, [ 16,32 ] is known to increase the effective mass of the electrons to 2.5 m 0 . [ 33 ] Phonon scattering may also affect the holes at the Γ point, which causes their heavy effective mass (2.57 m 0 ) and the strong thermal damping of the corresponding SdH oscillation.…”

Thermally induced band gap increase and high thermoelectric figure of merit of n-type PbTe

“…First-principles calculations of thermoelectric transport quantities are typically carried out using the electronic band structure obtained from density functional or higher level theories, where the band shifts due to temperature are not accounted for [12,13,14,15,16,17,18,19,20]. For example, recent abinitio calculations of TE transport in PbTe used a fixed band gap value at all temperatures [17].…”