Electrical detection of surface spin polarization of candidate topological Kondo insulator SmB6

Abstract

The Kondo insulator compound SmB6 has emerged as a strong candidate for the realization of a topologically nontrivial state in a strongly correlated system, a topological Kondo insulator, which can be a novel platform for investigating the interplay between nontrivial topology and emergent correlation driven phenomena in solid state systems. Electronic transport measurements on this material, however, so far showed only the robust surface dominated charge conduction at low temperatures, lacking evidence of its connection to the topological nature by showing, for example, spin polarization due to spin momentum locking. Here, we find evidence for surface state spin polarization by electrical detection of a current induced spin chemical potential difference on the surface of a SmB6 single crystal. We clearly observe a surface dominated spin voltage, which is proportional to the projection of the spin polarization onto the contact magnetization, is determined by the direction and magnitude of the charge current and is strongly temperature dependent due to the crossover from surface to bulk conduction. We estimate the lower bound of the surface state net spin polarization as 15 percent based on the quantum transport model providing direct evidence that SmB6 supports metallic spin helical surface states.

arXiv comment21 pages, 5 figures

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Cited by in corpus (8)

• Definitive Surface Magnetotransport Study of SmB${}_6$
• Probing FeSi, a d-electron topological Kondo insulator candidate, with magnetic field, pressure, and microwaves
• Unified Framework for Charge-Spin Interconversion in Spin-Orbit Materials
• Heisenberg machines with programmable spin-circuits
• Electrical detection of the inverse Edelstein effect on the surface of SmB${}_6$
• An STM perspective on hexaborides: Surface states of the Kondo insulator SmB${}_6$
• Unconventional Josephson junctions with topological Kondo insulator weak links
• Topological surface states in the Kondo insulator YbB${}_{12}$ revealed via planar tunneling spectroscopy