Valley Purcell effect for Two-dimensional Dirac Materials

Graphene, transition metal dichalcogenides (TMDs), and hexagonal boron nitrides (hBNs) are typical one-atom-thick two-dimensional (2D) Dirac materials, whose electronic behaviors are described by the Dirac equation rather than the ordinary Schrodinger equation. Valleys, local extrema in the electronic band structures, are one of the intriguing properties of such 2D Dirac materials. Valley degree of freedom plays the role of information carrier, promising novel optoelectronic applications. We present a theory of the valley Purcell effect, explaining the optical cavity-driven modification of the valley-selective exciton recombination. Design consideration for optical cavities of the high valley Purcell factor is also provided.