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Excitonic insulator in transition metal dichalcogenides (TMDs)

Giovedi 8 novembre 2018, ore 15.00, aula Seminari, terzo piano, edificio Fisica, Dipartimento FIM, Modena

Relatore: Seyedeh Samaneh Ataei

Abstract: We study the pressure induced electronic phase transition in bulk 2H-MoS2, an indirect gap layered material. By using accurate ab initio calculations based on the combined many body perturbation theory and density functional theory we calculate the exciton dispersion at different applied pressures showing that an excitonic instability appears at the pressure of 34 GPa, where the indirect electronic band gap is almost closed and the lowest indirect exciton present a binding energy of about 30 meV. The calculated pressure induced electronic band gap closure is well in line with the estimated metallisation onset (about 35-40 GPa) reported in previous theoretical and experimental results for this material. Our results give promising insights about the occurrence of a pure electronic instability and the realization of an excitonic insulator for a pressure slightly above the occurrence of the the pressure induced transition to metallic phase of bulk 2H- MoS2.

[Ultimo aggiornamento: 31/10/2018 11:10:23]