LAUSR

We study the exciton condensation phenomena in low-buckled two-dimensional semiconductors. Starting from the tight-binding effective Hamiltonian and considering the spin–orbit coupling as well as Rashba interaction induced by external electric field, we solve the gap equation analogous to BCS theory. Our calculation, with a careful analysis of Coulomb interaction, shows that the ground state is a mixture of s-wave and p-wave solutions. It is also a mixed state of singlet and triplet states and hence, can be probed with optical means. Furthermore, we studied the midgap state in a three-layer structure and proposed experiments to verify the existence of mixed states.