Phonon-limited electrical transport properties of intermetallic compound YbAl3 from first-principles calculations

TL;DR

This study uses first-principles calculations and Boltzmann transport theory to analyze the electrical transport properties of YbAl3, revealing the importance of scattering effects and size reduction for thermoelectric performance.

Contribution

It introduces a detailed first-principles approach to accurately predict electron-phonon scattering and transport properties in YbAl3, highlighting the significance of scattering in Seebeck coefficient calculations.

Findings

Scattering term significantly influences Seebeck coefficient calculations.

Reducing sample size below ~30 nm suppresses thermal conductivity.

Transport coefficients align well with experimental data.

Abstract

We combine first-principles calculations and Boltzmann transport theory to study the electrical transport properties of intermetallic compound YbAl3. To accurately predict the electronic relaxation time, we use the density functional perturbation theory and Wannier interpolation techniques which can effectively treat the electron-phonon scattering. Our calculated transport coefficients of YbAl3 are in reasonable agreement with the experimentally measured results. Strikingly, we discover that in evaluating the Seebeck coefficient of YbAl3, the scattering term has a larger contribution than the band term and should be explicitly considered in the calculations, especially for the case with localized bands near the Fermi level. Moreover, we demonstrate that by reducing the sample size to less than ~30 nm, the electronic thermal conductivity of YbAl3 can be sufficiently suppressed so that the thermoelectric figure of merit can be further enhanced.