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Comprehensive surface magnetotransport study of SmB 6

2020; American Physical Society; Volume: 101; Issue: 15 Linguagem: Inglês

10.1103/physrevb.101.155109

2469-9977

Yun Suk Eo, Steven Wolgast, Alexa Rakoski, Dmitri Mihaliov, Boyoun Kang, Myungsuk Song, B. K. Cho, Monica Ciomaga Hatnean, G. Balakrishnan, Z. Fisk, Shanta Saha, X. Wang, Johnpierre Paglione, Çağlıyan Kurdak,

Physics of Superconductivity and Magnetism

After the theoretical prediction that ${\mathrm{SmB}}_{6}$ is a topological Kondo insulator, there has been an explosion of studies on the ${\mathrm{SmB}}_{6}$ surface. However, there is not yet an agreement on even the most basic quantities such as the surface carrier density and mobility. In this paper, we carefully revisit Corbino disk magnetotransport studies to find those surface transport parameters. We first show that subsurface cracks exist in the ${\mathrm{SmB}}_{6}$ crystals, arising both from surface preparation and during the crystal growth. We provide evidence that these hidden subsurface cracks are additional conduction channels, and the large disagreement between earlier surface ${\mathrm{SmB}}_{6}$ studies may originate from previous interpretations not taking this extra conduction path into account. We provide an update of more reliable magnetotransport data than the previous one (S. Wolgast et al., Phys. Rev. B 92, 115110) and find that the orders-of-magnitude large disagreements in carrier density and mobility come from the surface preparation and the transport geometry rather than the intrinsic sample quality. From this magnetotransport study, we find an updated estimate of the carrier density and mobility of $2.71\ifmmode\times\else\texttimes\fi{}{10}^{13}$ (1/${\mathrm{cm}}^{2}$) and 104.5 (${\mathrm{cm}}^{2}$/$\mathrm{V}\phantom{\rule{0.16em}{0ex}}\mathrm{sec}$), respectively. We compare our results with other studies of the ${\mathrm{SmB}}_{6}$ surface. By this comparison, we provide insight into the disagreements and agreements of the previously reported angle-resolved photoemission spectroscopy, scanning tunneling microscopy, and magnetotorque quantum oscillations measurements.