Time-dependent dichroism and transient valley polarisation in monolayer transition metal dichalcogenides under finite-pulse radiation

Recent advances in time-resolved angle-resolved photoemission spectroscopy have enabled access to ultrafast electron states and their spin dynamics in solids. Atomically thin transition metal dichalcogenides are paradigmatic two-dimensional materials where electron momentum and spin degrees of freed...

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Bibliographic Details
Main Authors: Alejandro S Gómez, Yuriko Baba, Francisco Domínguez-Adame, Rafael A Molina
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:JPhys Materials
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Online Access:https://doi.org/10.1088/2515-7639/ade292
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Summary:Recent advances in time-resolved angle-resolved photoemission spectroscopy have enabled access to ultrafast electron states and their spin dynamics in solids. Atomically thin transition metal dichalcogenides are paradigmatic two-dimensional materials where electron momentum and spin degrees of freedom are coupled, being suitable candidates for time-resolved spectroscopy studies. In this work, we present a thorough study of the electron dynamics when these materials are subject to an intense finite-pulse driving radiation. We extend the scope of the conventional Floquet engineering and rely on the so-called $t-t^{^{\prime}}$ formalism to deal with driving fields described with two distinct time scales, namely the envelope amplitude timescale and the time period of the external field. The interplay between the finite-pulse timescales and the intrinsic properties of the electrons gives rise to transient valley polarisation and dynamical modifications of band structures, revealed by the time-dependent circular dichroism of the sample.
ISSN:2515-7639