Photoluminescent Quantum Interference in a van der Waals Magnet Preserved by Symmetry Breaking.

Abstract

Quantum interference gives rise to the asymmetric Fano resonance line shape when the final states of an electronic transition follow within a continuum of states and a discrete state, which has significant applications in optical switching and sensing. The resonant optical phenomena associated with the Fano resonance have been observed by absorption spectra, Raman spectra, transmission spectra, <i>etc.</i>, but have rarely been reported in photoluminescence (PL) spectroscopy. In this work, we performed spectroscopic studies on layered chromium thiophosphate (CrPS₄), a promising ternary antiferromagnetic semiconductor with PL in the near-infrared wavelength region and observed a Fano resonance when CrPS₄ experiences phase transition into the antiferromagnetic state below the Néel temperature (38 K). The photoluminescence of the continuum states results from the <i>d</i> band transitions localized at Cr³⁺ ions, whereas the discrete state is formed by an impurity level, the electronic transition of which is enabled by symmetry breaking. Our findings provide insights into the photon-emitting coherent electronic transitions of CrPS₄ and their connection to the magnetism-related broken symmetry.