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Gaku Eguchi, S. Paschen:
"Magnetotransport of Dirac fermion systems";
Vortrag: Japan Physical Society 2016 fall meeting, Kanazawa, Japan; 13.09.2016 - 16.09.2016.

Charge and spin transport in topologically protected electronic bands are fascinating topics of both fundamental and applied researches. The protected bands exhibit linear dispersion accompanying massless Dirac fermions, and a number of angle-resolved photoemission stud- ies have indeed demonstrated the presence of such bands, for instance in (Bi, Sb)2(Se, Te)3, TlBi(Te, Se)2, Cd3As2, and (Ta, Nb)(As, P) [1]. In electrical transport, the Dirac fermions result in high-mobility carriers. The transport properties have been discussed with values obtained from two-carrier analysis [2], however, the analysis is also known to exhibit huge errors. This is a fundamental issue known for decades [3], which complicates the interpretation of multi-carrier conduction. Recently, the issue has been overcome by a newly proposed analysis method [4], and a negligible contribution of the Dirac fermions was revealed in a bulk-metallic sample of TlBiSe2 [5]. The method was also applied to bismuth thin films, and revealed a dominance of electron conduction accompanying the positive Hall coefficient [6]. The approach determines the two-carrier transport properties with small errors, and thus the properties related to the Dirac fermions can be determined explicitly.
In this presentation we report a full description of the analysis [4], and present how to evaluate the two-carrier transport properties. Based on the analysis, Hall effect and magne- toresistance observed in the Dirac fermion systems are discussed.