Collective excitations and low temperature transport properties of bismuth

TL;DR

This paper investigates how collective excitations, especially an acoustic plasmon mode, influence the low-temperature transport and optical properties of bismuth, revealing a crossover in resistivity behavior and predicting a plasmon feature in magneto-optical spectra.

Contribution

It demonstrates the significant impact of an acoustic plasmon mode on bismuth's transport properties using RPA, and predicts observable features in magneto-optical conductivity.

Findings

Resistivity exhibits a T^5 dependence at low temperatures.

A crossover temperature T* separates different transport regimes.

Predicted a two plasmon edge feature in magneto-optical conductivity.

Abstract

We examine the influence of collective excitations on the transport properties (resistivity, magneto- optical conductivity) for semimetals, focusing on the case of bismuth. We show, using an RPA approximation, that the properties of the system are drastically affected by the presence of an acoustic plasmon mode, consequence of the presence of two types of carriers (electrons and holes) in this system. We found a crossover temperature T* separating two different regimes of transport. At high temperatures T > T* we show that Baber scattering explains quantitatively the DC resistivity experiments, while at low temperatures T < T* interactions of the carriers with this collective mode lead to a T^5 behavior of the resistivity. We examine other consequences of the presence of this mode, and in particular predict a two plasmon edge feature in the magneto-optical conductivity. We compare our results with the experimental findings on bismuth. We discuss the limitations and extensions of our results beyond the RPA approximation, and examine the case of other semimetals such as graphite or 1T-TiSe_2.