A theory of low-temperature resistivity for Alkali Metals

Author

Zhongcheng Wang

Date of Award

8-1989

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Gerald D. Mahan

Committee Members

Joachim Burgdorfer, J. R. Thompson, J. E. Bloor

Abstract

Two problems are discussed with respect to the theory of low-temperature resistivity for alkali metals. In Part I, an electron-dual-phonon scattering mechanism is considered. It was found that the low-temperature electrical resistivity ρ_dphfrom umklapp dual-phonon scattering processes follows nearly the same exponential rule, ρ_dph = BT⁴exp(-θ’/T), as results from umklapp single-phonon scattering, where θ’ is dependent on the minimum available wavevector of phonons and the coefficient is proportional to the square of the mass ratio of electron to ion. However, the constant θ’ found from dual-phonon processes is only half of that from single-phonon processes. It is expected that this scattering mechanism has a significant effect on the low-temperature resistivity of some light alkali metals with high Debye temperature, Θ_D, at very low temperatures. In Part II, the energy-balance equation in the Lei-Ting force-balance theory of nonlinear resistivity is discussed. In the Lei-Ting theory, the resistivity is determined by a set of two coupled equations, the force-balance equation and the energy-balance equation. The original derivation of the energy-balance equation is based on the assumption that the kinetic energy of the relative motion of the electrons in their center-of-mass coordinates does not change in the electrical transport, so that the energy supplied by the external field per unit time is absorbed only by the phonon system. Through a new approach of deriving this equation, it was found that the kinetic energy of the relative motion of the electrons cannot be considered as a constant in the electrical transport as assumed in the earlier theory. This implies that the power supplied by the electric field is not only absorbed by the phonons, but also increases the kinetic energy of the relative motion of the electrons.

Recommended Citation

Wang, Zhongcheng, "A theory of low-temperature resistivity for Alkali Metals. " PhD diss., University of Tennessee, 1989.
https://trace.tennessee.edu/utk_graddiss/11788