Electrical excitation of self-hybridized exciton polaritons in a van der Waals antiferromagnet.

The coupling of light with excitations in matter is one of the most important concepts to make photons interact, crucial for the development of efficient optoelectronic devices. In materials with exceptionally strong light-matter interaction, excitons can hybridize with photons without the need of an external cavity. Here, we report the electrical excitation of such self-hybridized polaritons in the van der Waals antiferromagnet CrSBr. We exploit an unconventional excitation via energy transfer from tunneling electrons in graphene tunnel junctions to strongly bound excitons in proximate CrSBr layers. This enables us to excite CrSBr crystals ranging in thickness from a bilayer up to 250 nanometers, with the strong linear polarization of the electroluminescence confirming the excitonic origin. We assign the electrically excited emission to self-hybridized exciton polaritons, highlighting the strong coupling between optical excitations and confined photon modes in CrSBr. Our findings not only offer an efficient method to generate polaritons electrically but also create opportunities for future spintronic devices.