Bidirectional effect of magnetic field on electronic thermal transport of metals from all-electron first-principles calculations

Abstract

Considerable discussions have occurred about the critical role played by free electrons in the transport of heat in pure metals. In principle, any environment that can influence the dynamical behaviors of electrons would have impact on electronic thermal conductivity $({\ensuremath{\kappa}}_{\mathrm{el}})$ of metals. Over the past decades, significant progress and comprehensive understanding have been gained from theoretical, as well as experimental, investigations by taking into account the effects of various conditions, typically temperature, impurities, strain, dimensionality, interface, etc. However, the effect of external magnetic field has received less attention. In this paper, the magnetic-field dependence of electron-phonon scattering, the electron's lifetime, and ${\ensuremath{\kappa}}_{\mathrm{el}}$ of representative metals (Al, Ni, and Nb) are investigated within the framework of all-electron spin-density functional theory. For Al and Ni, the induced magnetization vector field and difference in electron density under external magnetic-field aggregate toward the center of unit cell, leading to the enhanced electron-phonon scattering, the damped electron's lifetime, and thus the reduced ${\ensuremath{\kappa}}_{\mathrm{el}}$. On the contrary, for Nb with strong intrinsic electron-phonon interaction, the electron's lifetime and ${\ensuremath{\kappa}}_{\mathrm{el}}$ slightly increase as external magnetic field is enhanced. This is mainly attributed to the separately distributed magnetization vector field and difference in electron density along the corner of unit cell. This paper sheds light on the origin of influence of external magnetic field on ${\ensuremath{\kappa}}_{\mathrm{el}}$ for pure metals and offers a new route for robust manipulation of electronic thermal transport via applying external magnetic field.