Excitons under large pseudomagnetic fields

TL;DR

This paper demonstrates how large pseudomagnetic fields, generated by uniaxial strain, can reveal spintronic phenomena and fundamental properties of excitons in TMDs, opening pathways for pseudospin-based devices.

Contribution

It introduces a method to generate tunable pseudomagnetic fields in TMDs and explores their effects on excitons, including pseudospin phenomena and many-body state characterization.

Findings

Demonstrated pseudospin analogs of Zeeman effect and Larmor precession.

Measured depolarizing field strength affecting exciton coherence.

Uncovered bosonic nature of excitonic species via pseudomagnetic $g$-factor spectroscopy.

Abstract

Excitons in Transition Metal Dichalcogenides (TMDs) acquire a spin-like quantum number, a pseudospin, originating from the crystal's discrete rotational symmetry. Here, we break this symmetry using a tunable uniaxial strain, effectively generating a pseudomagnetic field exceeding 40 Tesla. Under this large field, we demonstrate pseudospin analogs of spintronic phenomena such as the Zeeman effect and Larmor precession. Moreover, we determine previously inaccessible fundamental properties of TMDs, including the strength of the depolarizing field responsible for the loss of exciton coherence. Finally, we uncover the bosonic -- as opposed to fermionic -- nature of many-body excitonic species using the pseudomagnetic equivalent of the $g$-factor spectroscopy. Our work is the first step toward establishing this spectroscopy as a universal method for probing correlated many-body states and realizing pseudospin analogs of spintronic devices.