Regensburg 2025 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 35: Topology: Poster

TT 35.1: Poster

Mittwoch, 19. März 2025, 15:00–18:00, P3

Conductive surface states in single-crystalline FeSi — •Philip Schröder, Gilles Gödecke, Julius Grefe, Stefan Süllow, and Dirk Menzel — Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany

The small-gap semiconductor FeSi exhibits an insulating ground state over a wide temperature range [1]. Notably, electric resistivity measurements imply the opening of a metallic transport channel at lowest temperatures, which historically has been attributed to conductivity among impurity levels [2]. However, recent transport studies on high-quality flux-grown FeSi single crystals discuss the conductive behavior in terms of metallic [3] and magnetic [4] surface states. We present (magneto-)resistance measurements on tri-arc Czochralski-grown FeSi single crystals in dependence of the sample thickness. The controlled manipulation of the surface-to-volume ratio by successive grinding of the specimen under investigation allows for separation of the bulk resistivity and the superimposed contribution of the surface channels. An effective two-channel model has been applied to approximate the upper limit of the surface conductivity.

[1] V. Jaccarino et al., Phys. Rev. 160, 476 (1967).

[2] S. Paschen et al., Phys. Rev. B 56, 12916 (1997).

[3] Y. Fang et al., Proc. Natl. Acad. Sci. U.S.A. 115, 8558 (2018).

[4] K. E. Avers et al., Phys. Rev. B 110, 134416 (2024).

Keywords: surface states; surface-to-volume ratio; electric transport properties