Polarization of photoluminescence by optically driven orbital reconstruction in magnetically ordered CrCl3

Abstract

Control of magnetic order through optical manipulation of orbital states can be realized in a wide range of materials, including insulators. In the latter case, electrons are excited into different electronic states, whose character may be a complex result of spin-orbit-lattice coupling. Here, we use a combination of polarization-resolved photoluminescence spectroscopy and density functional theory calculations to study excited Cr3+ ions in bulk, insulating antiferromagnetic CrCl3. Our results demonstrate a temperature-dependent preferential polarization direction below ~17 K, which reorients in the presence of an applied in-plane magnetic field. Density functional theory calculations reveal a local distortion of the ligand field and the generation of out-of-plane spin and orbital moments, following Cr3+ ion excitation. These changes link the photoluminescence polarization to the magnetic state of CrCl3. Our findings provide insight into the excited-state electronic structure of Cr3+ ions and suggest that CrCl3 is a promising candidate for opto-orbitronic applications.