Spin and orbital texture of quantum materials from dichroism in the ultrafast photoemission yield

Abstract

Exploring the ultrafast dynamics of quantum materials is crucial to understand their out-of-equilibrium behavior and the properties of their excited states. By using multi-dimensional time-resolved photoemission, we show that the dichroism in the photoemission yield is related to their orbital and spin texture, both for the filled and the empty electronic states. This is possible thanks to the use of an angle-resolved time-of-flight detector, which makes it possible to effectively measure the overall photoelectron yield and electronic band structure in reciprocal space. We present some relevant examples of this spectroscopic approach, which exploits the polarization control of ultrafast laser sources, applied to the study of Dirac fermions in prototype topological materials such as Bi₂Se₃ and Bi₂Te₂Se.