Tuning inelastic light scattering via symmetry control in the two-dimensional magnet CrI.

The coupling between spin and charge degrees of freedom in a crystal gives rise to magneto-optical effects with applications in the sensitive detection of local magnetic order, optical modulation and data storage. In two-dimensional magnets these effects manifest themselves in the large magneto-optical Kerr effect, spontaneous helical light emission from ferromagnetic (FM) monolayers and electric-field induced Kerr rotation and giant second-order non-reciprocal optical effects in antiferromagnetic (AFM) bilayers. Here we demonstrate the tuning of inelastically scattered light through symmetry control in atomically thin chromium triiodide (CrI).

Signatures of moiré-trapped valley excitons in MoSe/WSe heterobilayers.

The formation of moiré patterns in crystalline solids can be used to manipulate their electronic properties, which are fundamentally influenced by periodic potential landscapes. In two-dimensional materials, a moiré pattern with a superlattice potential can be formed by vertically stacking two layered materials with a twist and/or a difference in lattice constant. This approach has led to electronic phenomena including the fractal quantum Hall effect, tunable Mott insulators and unconventional superconductivity.