Year: 2019
Type: article
Abstract: Lifting the valley degeneracy of monolayer transition metal dichalcogenides (TMDs) would allow versatile control of the valley degree of freedom. We report a giant valley exciton splitting of 16 meV/T for monolayer WS 2 , using the proximity effect from an EuS substrate, which is enhanced by nearly two orders of magnitude from that obtained by an external magnetic field. More interestingly, a sign reversal of the valley splitting is observed as compared to that of WSe 2 on EuS. Using first principles calculations, we investigate the complex behavior of exchange interactions between TMDs and EuS. The sign reversal is attributed to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions for Eu- and S- terminated EuS surface sites. They act differently on the conduction and valence bands of WS 2 compared to WSe 2 . Tuning the sign and magnitude of the valley exciton splitting offers opportunities for control of valley pseudospin for quantum information processing.
Source: Nature Communications
Authors: Tenzin Norden, Chuan Zhao, Peiyao Zhang, Renat Sabirianov, Athos Petrou, Hao Zeng
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $5,200
Awards: Heterojunction Solar Cells Using Chemically co-doped Titania Nanotube Arrays for Simultaneous Light Absorption and Carrier Transport, SusChEM: Collaborative Research: Hybrid perovskite inspired pathways towards green and stable ionic PV absorbers, MRI: Acquisition of a Hybrid Sputtering/e-beam Thin Film Deposition System for Research and Education, G6542609337, G8829243878
OpenAlex ID: W2913250816