Recently, anomalous energy bands with negative mass attract intensive attention where non-Hermiticity plays an important role. In this work, we observe anomalous exciton-polariton bands in (PEA)2PbI4 perovskite based microcavity at room temperature. We simulate the anomalous band structure using a non-Hermitian coupled oscillator model, which agrees with experiments very well. Our results offer to study non-Hermitian polariton wave dynamics at room temperature.
Xing et al. (2026) studied this question.