Four Terahertz Plasmon Modes of Hole Gas in Monolayer MoS2

We investigate on the terahertz (THz) plasmons of hole gas in monolayer MoS2 in the presence of spin-orbit interactions (SOIs) under the random phase approximation. The study shows that four THz plasmon modes can be achieved via intra- and inter-spin-subband transitions in p-doped monolayer MoS2. The two plasmons induced by intra-spin-subband transitions are acoustic-like, while the other two plasmon modes via inter-spin-subband transitions are optic-like. The frequencies of the four plasmons strongly depend on the hole density and the two plasmon modes induced by inter-spin-subband transitions are sensitive on the spin polarizability. Our theoretical results reveal that the plasmons in monolayer MoS2 can be applied to realize THz plasmonic devices, such as THz source emitters.