Quantum oscillations in the heat capacity of Kondo insulator YbB12

TL;DR

This study reports the detection of quantum oscillations in the heat capacity of the Kondo insulator YbB12, indicating charge-neutral fermions and providing insights into its electronic structure.

Contribution

First observation of quantum oscillations in heat capacity of YbB12, revealing charge-neutral fermions and their effective mass in a Kondo insulator.

Findings

Quantum oscillations observed in heat capacity at 0.8 K.

Oscillation frequency F = 670 T matches magnetoresistance data.

Oscillation amplitude accounts for 13% of the linear heat capacity.

Abstract

We observe the magnetic quantum oscillation in the heat capacity of the Kondo insulator YbB$_{12}$. The frequency of these oscillations $F = 670$ T, aligns with findings from magnetoresistance and torque magnetometry experiments for $\mu_0 H > 35$ T in the Kondo insulating phase. Remarkably, the quantum oscillation amplitudes in the heat capacity are substantial, with $\Delta \tilde{C}/T \approx$ 0.5 $\rm{mJ}$ $\rm{mol^{-1}K^{-2}}$ at 0.8 K, accounting for 13$\%$ of the known linear heat capacity coefficient $\gamma$. Double-peak structures of quantum-oscillation amplitudes due to the distribution function of fermions were identified and used to determine the value of the effective mass from the heat capacity, which agrees well with that from torque magnetometry. These observations support charge-neutral fermions contributing to the quantum oscillations in YbB$_{12}$.