DoP Colloquium - Dino Novko

Exploring complex quantum phases of transition metal dichalcogenides
(Dino Novko - Institute of Physics, Zagreb)

Precise microscopic calculations of electron-phonon coupling are central for understanding various physical phenomena in condensed matter physics, such as thermal and electronic transport, phonon-assisted absorption, carrier thermalization, superconducitvity, and structural phase transitions. In this talk I will present several recent results from our group where we use state-of-the-art many-body techniques in combination with density functional theory in order to understand the origin of complex quantum phases in TiSe2 and their connection to the electron-phonon coupling. The phase diagram of TiSe2 is characterized with unusual charge density wave (CDW), which is considered one of the earliest examples of excitonic insulator, a phase where electron-hole bound state is spontaneously formed. On the other hand, a more conventional origin, i.e., electron-phonon coupling, of this CDW was also discussed, however, without the final conclusion. Here I provide our contribution to this debate, where we create a phase diagram of various collective excitations, which eventually help us to understand the formation mechanisms of CDW in TiSe2.