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Long-lived spin plasmons in a spin-polarized two-dimensional electron gas
Journal article   Peer reviewed

Long-lived spin plasmons in a spin-polarized two-dimensional electron gas

Amit Agarwal, Marco Polini, Giovanni Vignale and Michael E Flatte
Physical review. B, Condensed matter and materials physics, Vol.90(15), 155409
06/04/2014
DOI: 10.1103/PhysRevB.90.155409
url
https://arxiv.org/pdf/1406.0986View
Open Access

Abstract

Phys. Rev. B 90, 155409 (2014) Collective charge-density modes (plasmons) of the clean two-dimensional unpolarized electron gas are stable, for momentum conservation prevents them from decaying into single-particle excitations. Collective spin-density modes (spin plasmons) possess no similar protection and rapidly decay by production of electron-hole pairs. Nevertheless, if the electron gas has a sufficiently high degree of spin polarization ($P>1/7$, where $P$ is the ratio of the equilibrium spin density and the total electron density, for a parabolic single-particle spectrum) we find that a long-lived spin-plasmon---a collective mode in which the densities of up and down spins oscillate with opposite phases---can exist within a "pseudo gap" of the single-particle excitation spectrum. The ensuing collectivization of the spin excitation spectrum is quite remarkable and should be directly visible in Raman scattering experiments. The predicted mode could dramatically improve the efficiency of coupling between spin-wave-generating devices, such as spin-torque oscillators.
 Physics - Mesoscale and Nanoscale Physics

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