Quantum oscillations in interaction-driven insulators

In recent years it has become understood that quantum oscillations, long recognized as phenomena intrinsic to metals, can manifest in insulating systems as well. Simple models have shown that in band insulators oscillations can appear with a frequency set by the area in momentum space traced out by the minimum gap. Here we examine quantum oscillations in Kondo and excitonic insulators, systems for which the band gap is generated by interaction effects. In both cases, the gapped band structure is dependent on parameters that are determined self-consistently and vary with the applied magnetic field strength, so that the bands are not "rigid" as the field changes and new contributions to quantum oscillations can be generated on top of what is expected from a simple band insulator. We analyze these contributions in the low-temperature, low-field regime, finding that they do not contribute to the lowest harmonic of quantum oscillations but provide the dominant contribution to all higher harmonics. We also examine the contribution from fluctuations of the insulating order.