Optoelectronic control of spin dynamics at near-THz frequencies in magnetically doped quantum wells

TL;DR

This paper demonstrates the optical and electrical control of spin dynamics at near-THz frequencies in magnetically doped quantum wells, showing tunable electron and Mn spin precession via bias and laser energy adjustments.

Contribution

It introduces a method to electrically and optically tune spin dynamics in magnetically doped quantum wells, achieving significant modulation of precession frequencies and amplitudes.

Findings

Electron spin precession frequency varies from 0.1 to 0.8 THz.

Electrical bias modulates Mn spin precession amplitude and lifetime.

Large variation in spin dynamics due to changes in sp-d exchange overlap.

Abstract

We use time-resolved Kerr rotation to demonstrate the optical and electronic tuning of both the electronic and local moment (Mn) spin dynamics in electrically gated parabolic quantum wells derived from II-VI diluted magnetic semiconductors. By changing either the electrical bias or the laser energy, the electron spin precession frequency is varied from 0.1 to 0.8 THz at a magnetic field of 3 T and at a temperature of 5 K. The corresponding range of the electrically-tuned effective electron g-factor is an order of magnitude larger compared with similar nonmagnetic III-V parabolic quantum wells. Additionally, we demonstrate that such structures allow electrical modulation of local moment dynamics in the solid state, which is manifested as changes in the amplitude and lifetime of the Mn spin precession signal under electrical bias. The large variation of electron and Mn-ion spin dynamics is explained by changes in magnitude of the sp−d exchange overlap.