Researcher aids understanding of collective excitations in MoS2

Dr. Željana Bonačić Lošić from the Department of Physics, Faculty of Science at the University of Split, Croatia, has studied the coupling of plasmon and dipolar collective modes in a monolayer of molybdenum disulfide. Collective excitations play a key role in describing any many-body quantum system. A monolayer of molybdenum disulfide is a promising two-dimensional material that has attracted much attention lately because of its potential applications. In this sense, the investigation of its electronic properties is of special interest. The large direct band gap in a monolayer of MoS2 separating the valence and conduction bands leads to the appearance of the interband dipolar mode which couples to the intraband plasmon.

This results in two hybridized modes. The renormalized dipolar mode is close to its bare value, while coupling suppresses the plasmon mode. Also, the obtained modes are responsible for the appearance of dispersing peaks in the energy-loss function. This result is useful for our understanding of the collective excitations in MoS2.

"Our calculated collective mode peaks in the energy-loss function should be directly observable in momentum-resolved low energy electron energy-loss spectroscopy (EELS) as previously observed plasmon peak in graphene," says Dr. Željana Bonačić Lošić.

The report appears in Modern Physics Letters B.