CNR NANO - Istituto Nanoscienze Consiglio Nazionale delle Ricerche

- 08.11.2018 - COLLOQUIA 2018 S3 SEMINAR
Date and Time: Thursday November 8, 2018 - 15.00
Venue: S3 Seminar Room, Third Floor, Physics Building, FIM Department

Speaker: Seyedeh Samaneh Ataei

Title: Excitonic insulator in transition metal dichalcogenides (TMDs)

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.

Host: Massimo Rontani