Electron spin relaxation in carbon nanotubes

TL;DR

This paper investigates the mechanisms behind rapid electron spin relaxation in carbon nanotubes, attributing it to curvature-induced spin-orbit interactions and valley interference, with implications for spin-based applications.

Contribution

It demonstrates that curvature-mediated spin-orbit coupling causes fast spin relaxation in CNTs, providing quantitative estimates and explaining experimental discrepancies.

Findings

Spin relaxation times as short as 150 ps and 110 ps at room temperature.

Pronounced anisotropic dependence of relaxation times.

Valley interference can accelerate dephasing.

Abstract

The long standing problem of inexplicably short spin relaxation in carbon nanotubes (CNTs) is examined. The curvature-mediated spin-orbital interaction is shown to induce fluctuating electron spin precession causing efficient relaxation in a manner analogous to the Dyakonov-Perel mechanism. Our calculation estimates longitudinal (spin-flip) and transversal (decoherence) relaxation times as short as 150 ps and 110 ps at room temperature, respectively, along with a pronounced anisotropic dependence. Interference of electrons originating from different valleys can lead to even faster dephasing. The results can help clarify the measured data, resolving discrepancies in the literature.