Microwave Absorption for Detection of Dirac Fermions in SnTe Films

ABSTRACT This work investigates SnTe thin films using microwave absorption as a probe for the presence of Dirac fermions. Shubnikov–de Haas oscillations observed in the microwave absorption signal were analyzed for both uncapped and capped samples, where a BaF 2 cap layer was employed to protect the topological surface states from degradation. Unexpectedly, signatures of Dirac fermions were also detected in the uncapped sample, despite previous magnetotransport measurements showing no evidence of their presence. This finding provides strong evidence that the topological surface states are robust against deterioration due to atmospheric exposure and that microwave absorption measurements can reveal these states even when they are not accessible through transport measurements. Furthermore, Zeeman splitting was observed in the fast Fourier transform of the oscillations, indicating the presence of low‐mobility channels that had previously been detected only at higher magnetic fields.