Università Cattolica del Sacro Cuore

Spin- and time resolved ARPES studies of transition metal dichalcogenides

Seminario  4 maggio 2017
Aula: Sala Riunioni -  Ore: 15.00
Via Musei 41, Brescia

Spin- and time resolved ARPES studies of transition metal dichalcogenides

Introduce:
Dott. Claudio Giannetti
Università Cattolica del Sacro Cuore

Interviene:
Dott. Elia RAZZOLI
University of British Columbia, Vancouver, Canada

Abstract

Transition metal dichalcogenides display a plethora of interesting properties from coupled spin and valley physics in the semiconducting 2H structure to type II Weyls fermions in the non-centrosymmetric 1T’ structure. Here we will firstly show how spin- and angle-resolved photoemission spectroscopy provide evidence for a large spin polarization P in the bulk of centrosymmetric MoS2, and how this can be reversed by changing the handedness of the incident circularly polarized light. Our calculations show that the valley and layer-locked spin-polarized electronic states can be selectively accesses by circularly polarized light, therefore providing a novel route to probe spin-polarized states in inversion-symmetric systems [1]. Secondly, we will present a pump-probe time-resolved ARPES study of the relaxation dynamics in the candidate type II Weyl-semimetal WTe2. We identify fast and slow components in the electron relaxation dynamics, which display a strong dependence on both the electron momentum k and temperature. The interplay between the temperature evolution of this dynamics, details of the electronic band structure, and putative Weyl quasiparticle behavior, will be discussed.



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