Direct observation of surface state thermal oscillation in SmB6 oscillators

Abstract

SmB6 is a mixed valence Kondo insulator that exhibits a sharp increase in resistance following an activated behavior that levels off and saturates below 4K. This behavior can be explained by the proposal of SmB6 representing a new state of matter, a Topological Kondo insulator, in which a Kondo gap is developed and topologically protected surface conduction dominates low-temperature transport. Exploiting its non-linear dynamics, a tunable SmB6 oscillator device was recently demonstrated, where a small DC current generates large oscillating voltages at frequencies from a few Hz to hundreds of MHz. This behavior was explained by a theoretical model describing the thermal and electronic dynamics of coupled surface and bulk states. However, a crucial aspect of this model, the predicted temperature oscillation in the surface state, hasn't been experimentally observed to date. This is largely due to the technical difficulty of detecting an oscillating temperature of the very thin surface state. Here we report direct measurements of the time-dependent surface state temperature in SmB6 with a RuO micro-thermometer. Our results agree quantitatively with the theoretically simulated temperature waveform, and hence support the validity of the oscillator model, which will provide accurate theoretical guidance for developing future SmB6oscillators at higher frequencies.

arXiv comment6 pages, 6 figures

References in corpus (14)

• Topological insulators and superconductors
• Topological Kondo Insulators
• Low-temperature surface conduction in the Kondo insulator SmB${}_6$
• Correlated Topological Insulators with Mixed Valence
• Topological surface state in the Kondo Insulator Samarium Hexaboride
• Quantum oscillations in Kondo Insulator SmB${}_6$
• Robust Surface Hall Effect and Nonlocal Transport in SmB6: Indication for an Ideal Topological Insulator
• Topological Kondo Insulators
• A theory of Topological Kondo Insulators
• Cubic Topological Kondo Insulators
• Hybridization, Inter-Ion Correlation, and Surface States in the Kondo Insulator SmB6
• One-dimensional edge state transport in a topological Kondo insulator
• Suppression of magnetic excitations near the surface of the topological Kondo insulator SmB6
• Radio Frequency Tunable Oscillator Device Based on SmB6 Microcrystal

Cited by in corpus (2)

• An STM perspective on hexaborides: Surface states of the Kondo insulator SmB${}_6$
• Slow crystalline electric field fluctuations in the Kondo lattice SmB${}_6$