Transport property of multi-band topological material PtBi_2 studied by maximum entropy mobility spectrum analysis (MEMSA)

Haijun Zhao,Weidong Luo,Yue Chen,Dong Qian,Zhixiang Shi,Chunqiang Xu,Bin Li,Wenchong Li

doi:10.1038/s41598-021-85364-6

Abstract

Electrical transport of both longitudinal and transverse directions carries rich information. Mobility spectrum analysis (MSA) is capable of extracting charge information from conductivity tensor, including charge types, concentration and mobilities. Using a numerical method based on maximum entropy principle, i.e., maximum entropy mobility spectrum analysis (MEMSA), mobility spectrum for beta -type PtBi_2 is studied. Three hole-pockets and two electron-pockets were found, including a small hole pocket with very high mobility, which is very likely corresponding to Dirac Fermions. Benefiting from our high resolution result, we studied temperature dependence of carrier properties and explained the sign change phenomenon of Hall conductivity. We further compared the results with band structure obtained by our first principle calculation. The present results prove MEMSA is a useful tool of extracting carries’ information in recently discovered Iron-based superconductors, and topological materials.

Highlights

Electrical transport of both longitudinal and transverse directions carries rich information
It is clear that comparing previous methods[25,27], our maximum entropy mobility spectrum analysis (MEMSA) method perfectly fits the experimental data of conductivity σxx and Hall conductivity σxy spontaneously
We demonstrate that MEMSA can identify carrier type, and get band number, and can calculate many other important information, including mobility, concentration, and conductivity contribution

Summary

Introduction

Electrical transport of both longitudinal and transverse directions carries rich information. Benefiting from our high resolution result, we studied temperature dependence of carrier properties and explained the sign change phenomenon of Hall conductivity. The present results prove MEMSA is a useful tool of extracting carries’ information in recently discovered Iron-based superconductors, and topological materials. Two examples of topological semimetals are: Dirac semimetals, which possess fourfold degenerate band crossings in momentum space, and Weyl semimetals, in which the spin degeneracy is lifted. The threefold point fermions have been indicated might exist in the materials with WC-type structure, such as MoP, WC, TaN and ZrTe10,14,15, which can be viewed as an intermediate state between fourfold degenerate Dirac points and twofold degenerate Weyl points. The carrier property can be measured by angle-resolved photoemission spectroscopy (ARPES) Benefitting from this measurement, the first experimental observations of the Dirac-cone states in IBSC were successfully m ade[16]. None of the above measurements can estimate the conductivity contributions from different bands

Results

Discussion

Conclusion