Crossover of Magnetoresistance from Fourfold to Twofold Symmetry in SmB₆ Single Crystal, a Topological Kondo Insulator

Abstract

Topological Kondo insulators have been attracting great attention from the condensed-matter physics community due to their fascinating topological and strongly correlated properties. Here, we report angledependent c-axis magnetoresistance (MR) oscillations in a Kondo insulator, SmB 6 single crystal, in a magnetic field of up to 13 T rotated in the ab-plane. Four-fold symmetric MR oscillations are first observed above 8 K, which result from the four-fold (C 4 ) degeneracy of the bulk Fermi surface of SmB 6 . With decreasing temperature down to 2.3 K, the C 4 symmetry of the MR oscillations gradually weakens and C 2 symmetry appears. This demonstrates a crossover from three-dimensional bulk states to two-dimensional surface states and implies the possible emergence of topological nematic states. Our experimental observations shed new light on the metallic surface states and nematic states in the Kondo insulator SmB 6 .

Topological surface states interacting with bulk excitations in the Kondo insulator SmB 6 revealed via planar tunneling spectroscopy

“…The rapid conductance jump below 5-6 K and subsequent saturation indicate that protected (or coherent) low-energy surface states may exist only in this low temperature region as the interaction with spin excitons becomes negligible. Similar abrupt changes in several other experiments (34,35) could also be understood by following this reasoning. A more deepened understanding of the tunneling process, particularly regarding the relevant length scales (33,36) and their temperature evolution (SI Appendix, section 12), is expected to facilitate progress toward a more comprehensive picture of the topological states arising in strongly correlated electron systems.…”

Pressure-induced quantum phase transitions in aYbB6single crystal

“…Theoretical calculations point out that the low temperature residual conductance in SmB 6 is originated from the non-trivial conducting surface state due to the hybridization between d-orbitals and f-orbitals of Sm ions [22]. Soon after, these predictions have been identified by many experimental measurements [12,13,17,20,21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36]. These results support that SmB 6 is a topological Kondo insulator (TKI).…”

Cross-over from weak localization to anti-localization in rare earth doped TRS protected topological insulators

“…Magneto-transport measurements represent an important approach to explore the electronic characteristics of quantum materials. [19][20][21][22][23][24][25] Magnetoresistance (MR = (RH-R0)/R0 × 100%) is the change of electrical resistance of a material in an externally-applied magnetic field. has wide applications in magnetic data storage, magnetic sensors, and magnetoelectronic devices.…”