Oscillators*

SmB₆ is a mixed valence Kondo insulator that has been proposed to be a topological Kondo Insulator with a Kondo insulating gap in the bulk and a gapless Dirac state on the surface. 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. Here we report direct measurements of the time-dependent surface state temperature in SmB₆ with a RuO₂ 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 SmB₆ oscillators at higher frequencies.