Robust local and nonlocal transport in the topological Kondo insulatorSmB6in the presence of a high magnetic field

Abstract

. (2015) Robust local and nonlocal transport in the topological Kondo insulator SmB6in the presence of a high magnetic field. Physical Review B, 92 (8). 085103. Permanent WRAP URL:http://wrap.warwick.ac.uk/87833 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement: © 2015 American Physical Society A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.For more information, please contact the WRAP Team at: wrap@warwick.ac.uk Robust local and non-local transport in the Topological Kondo Insulator SmB 6 in the presence of high magnetic field SmB6 has been predicted to be a Kondo Topological Insulator with topologically protected conducting surface states. We have studied quantitatively the electrical transport through surface states in high quality single crystals of SmB6. We observe a large non-local surface signal at temperatures lower than the bulk Kondo gap scale. Measurements and finite element simulations allow us to distinguish unambiguously between the contributions from different transport channels. In contrast to general expectations, the electrical transport properties of the surface channels was found to be insensitive to high magnetic fields. Local and non-local magnetoresistance measurements allowed us to identify definite signatures of helical spin states and strong inter-band scattering at the surface.

Probing the interplay between surface and bulk states in the topological Kondo insulatorSmB6through conductance fluctuation spectroscopy

“…The value of l φ at 20 mK obtained from the low-field-magnetoconductance fluctuation data using Eq. (1) is ∼1400 nm, which is quite close to the value found from WAL (∼1200 nm) [19,26], showing that these are indeed UCFs. Also, the value of (δG) 2 1/2 obtained at 20 mK from the time series of resistance fluctuations (using the data presented in Fig.…”

“…The local voltage v l increased by more than four orders of magnitude as the sample was cooled down from room temperature, which attests to the high purity of the SmB 6 crystals. The nonlocal voltage appeared below ∼10 K and increased rapidly by more than six orders of magnitude before saturating below T = 3 K. We showed in a previous publication that the appearance of this nonlocal transport signal can be attributed to SSs, which creates an additional transport channel in parallel with the bulk of the sample [19]. Using the method described in Ref.…”

“…The PSD S V (f ) ∝ 1/f α , with α ∼ 0.9-1.05. Magnetoresistance shows signatures of weak antilocalization (WAL) [19,26]. Observation of WAL implies strong effects of interference of electronic wave functions on the transport properties.…”

“…Using the method described in Ref. [19], the values of R s and R b were extracted from the measured v l and are plotted in Fig. 1(b).…”

Comprehensive surface magnetotransport study of SmB6

“…Also, from the historical perspective of the 2D electron gas studies, dHvA quantum oscillations have been more challenging to observe than the SdH oscillations, because the total magnetic moments are very small in a typical 2D electron layer 31 . Although not a disagreement in the strict sense, it is peculiar that Shubnikov de-Haas (SdH) quantum oscillations through dc electrical transport have not been observed even up to ∼80 T, 32 although dHvA has been reported with an onset lower than 10 T. In electrical transport, weak anti-localization (WAL), which is a supporting evidence of the helical spin structure on the TI surface, has been reported [33][34][35] ; however, there is also a report that WAL may not be universal possibility because of the magnetic impurities existing on the surface 7 . As we will show in this study, there are a number of transport experiments such as Hall effect, thermal transport, etc., but these electrical transport experiments report conductivity (σ 2D ), carrier density (n 2D ) and mobility (µ 2D ) in a wide (orders of magnitude) range of different values.…”