Robust Surface States indicated by Magnetotransport in SmB6 Thin Films

Abstract

SmB6 has been predicted and verified as a prototype of topological Kondo insulators (TKIs). Here we report longitudinal magnetoresistance and Hall coefficient measurements on co-sputtered nanocrystalline SmB6 films and try to find possible signatures of their topological properties. The magnetoresistance (MR) at 2 K is positive and linear (LPMR) at low field and becomes negative and quadratic at higher field. While the negative part is known from the reduction of the hybridization gap due to Zeeman splitting, the positive dependence is similar to what has been observed in other topological insulators (TI). We conclude that the LPMR is a characteristic feature of TI and is related to the linear dispersion near the Dirac cone. The Hall resistance shows a sign change around 50 K. It peaks and becomes nonlinear at around 10 K then decreases below 10 K. This indicates that carriers with opposite signs emerge below 50 K. Two films with different geometries (thickness and lateral dimension) show contrasting behavior below and above 50K, which proves the surface origin of the low temperature carriers in these films. The temperature dependence of magnetoresistance and the Hall data indicates that the surface states are likely non-trivial.

16 pages, 4 figures

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Cited by in corpus (5)

• Observation of the superconducting proximity effect in the surface state of SmB6 thin films
• Ultrafast terahertz spectroscopy study of Kondo insulating thin film SmB${}_6$: evidence for an emergent surface state
• Dirac-Kondo semimetals and topological Kondo insulators in the dilute carrier limit
• Electrical properties of SmB${}_6$ thin films prepared by pulsed laser deposition from a stoichiometric SmB${}_6$ target
• Low temperature resistivity studies of SmB6: Observation of twodimensional variable-range hopping conductivity