Pure spin current injection of single-layer monochalcogenides

TL;DR

This study calculates pure spin current injection in single-layer monochalcogenides, revealing high spin velocities and polarization independence, highlighting their potential for spintronics applications.

Contribution

It introduces a detailed first-principles calculation of spin velocity injection in these materials, showing their suitability for spintronics.

Findings

Peak spin velocities of 250, 210, 180, and 154 km/s for SnS, SnSe, GeS, and GeSe.

Spin velocity is independent of light polarization direction.

Velocities are an order of magnitude larger than in bulk semiconductors.

Abstract

We compute the spectrum of pure spin current injection in ferroelectric single-layer SnS, SnSe, GeS, and GeSe. The formalism takes into account the coherent spin dynamics of optically excited conduction states split in energy by spin orbit coupling. The velocity of spins is calculated as a function of incoming photon energy and angle of linearly polarized light within a full electronic band structure scheme using density functional theory. We find peak speeds of 250, 210, 180 and 154 Km/s for SnS, SnSe, GeS and GeSe, respectively which are an order of magnitude larger than those found in bulk semiconductors, e.g., CdSe and GaAs. Interestingly, the spin velocity is independent of the direction of polarization of light in a range of photon energies. Our results demonstrate that single-layer SnS, SnSe, GeS and GeSe are candidates to produce on demand spin-velocity injection for spintronics applications.