Phonon-limited transport and Fermi arc lifetime in Weyl semimetals

Il giorno Venerdì 25 Marzo alle ore 15:00 in aula 2G26 il Dr. Alessandro De Martino, Senior Lecturer at City University of  London, terrà un seminario dal titolo:
"Phonon-limited transport and Fermi arc lifetime in Weyl semimetals"
Weyl semimetals are a new class of quantum materials characterized by isolated band-crossing points in the Brillouin zone, the so-called Weyl nodes. Close to these points, electrons effectively behave as relativistic Weyl fermions with linear energy dispersion. They carry a topological charge, associated to their chirality. Due to the non-trivial topology, Weyl semimetals harbor Fermi-arc surface states which determine the nontrivial charge current response to external fields. In this talk, I will discuss the decay rate of Fermi arc states arising from their coupling to acoustic phonons, and the effects of electron-phonon coupling on the electric transport in a clean Weyl semimetal slab. I will show that the decay rate of the Fermi-arc states depends on the position along the arc. Then, by solving the coupled Boltzmann equations for the bulk and arc state distribution functions in the slab geometry, I will discuss the dependence of the conductivity on key parameters such as the temperature, the chemical potential, the geometric shape of the Fermi arcs, or the slab width. The chiral nature of Fermi arc states causes an enhancement of the longitudinal conductivity along the chiral direction at low temperatures, together with a 1/T^2 scaling regime at intermediate temperatures without counterpart for the conductivity along the perpendicular direction. 
Vittorio Cataudella e Procolo Lucignano
Data: 25/03/2022