Tunable valleytronics with symmetry-retaining high polarization degree in SnS x Se 1−x model system

Date Published
02/2020
Publication Type
Journal Article
Authors
DOI
10.1063/1.5128717
Abstract

SnS has recently been shown to possess unique valleytronic capability with a large polarization degree, where non-degenerate valleys can be accessed using linearly polarized light, bestowed upon by the unique anisotropy and wavefunction symmetry. It is thus of utmost importance to demonstrate the extension of such effects for the IV–VI system in general, thereby elucidating the generality and tunability of such valleytronics. We show the highly tunable valleytronics via gradual compositional control of the tin(II) sulfo-selenide (SnSxSe1x) alloy system with excellent retainment of symmetry-determined selection rules. We show the presence of both CY and CX valleys in all alloy compositions via selectivity in absorption and emission of linearly polarized light by optical reflection (R)/transmission (T) and photoluminescence measurements and tuned the bandgaps of the valleys within a range of 1.28 eV–1.05 eV and 1.48 eV–1.24 eV, respectively. This simultaneous tuning of non-degenerate valleys agrees well with theoretical calculations. We then fitted the bandgap values in compositional space, obtaining bowing parameters as a useful database. We further demonstrated the feasibility of using IV–VI valleytronics systems in general by elucidating the retainment of strong polarization degrees of as high as 91% across all compositions. The generalization of such purely symmetry-dependent valleytronics also opens up opportunities for the discovery of more multi-functional materials.

Journal
Applied Physics Letters
Volume
116
Year of Publication
2020
Issue
6
Pagination
061105
ISSN Number
0003-6951
Short Title
Appl. Phys. Lett.
Refereed Designation
Refereed
Organizations
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