Anomalous magnetic field dependence of theT1spin lifetime in a lightly doped GaAs sample

Abstract

The T 1 spin lifetime of a lightly doped n-type GaAs sample has been measured via time-resolved polarization spectroscopy under a number of temperature and magnetic field conditions. Lifetimes up to 19 s have been measured. The magnetic field dependence of T 1 shows a nonmonotonic behavior, where the spin lifetime first increases, then decreases, then increases again with field. The initial increase in T 1 is understood to be due to correlation between electrons localized on donors. The decrease in T 1 is likely due to phonon-related spin-orbit relaxation. The final increase in T 1 with B indicates a suppression of the spin-orbit relaxation that may involve a level-crossing related cusp in the Rashba or Dresselhaus contributions to relaxation, or may arise from an unknown source.

Spin dynamics in semiconductors

“…Experimental results on the magnetic field dependence of spin lifetime are available in Ref. [511]. Yet the observed magnetic field dependence has still to be explained by theory [511].…”

“…[511]. Yet the observed magnetic field dependence has still to be explained by theory [511]. Before turning to experimental studies, it should be mentioned that to date there have only been a few theoretical works on spin relaxation in the insulating regime [39,40,[322][323][324]324,325,443,507,510,512,513], more studies are needed.…”

“…We now review the experimental studies on carrier spin relaxation at low temperature in the insulating regime. Many efforts have been devoted to the spin relaxation in n-GaAs at low temperature [4,39,144,321,497,[501][502][503]511,[514][515][516][517][518][519][520][521]. In one of the seminal works, by Kikkawa and Awschalom [4], a surprisingly long spin lifetime (130 ns) was observed in n-GaAs, which sheds light on the possibility of semiconductor spintronics.…”

Semiconductor spin noise spectroscopy: Fundamentals, accomplishments, and challenges

“…Further, the strong temperature dependence reported in Refs. [178] and [179] is not found via SNS [48] and may also be an indication of insufficient cooling of the carrier system. With increasing doping density, spin dephasing originating from hyperfine interaction becomes more and more inefficient while the processes based on anisotropic exchange interaction (see Sec.…”

“…In the following paragraphs, we give a survey on the existing investigations via SNS on n-type bulk GaAs, modulation-doped (110) GaAs/AlGaAs quantum wells and unintentionally p-doped self assembled (In,Ga)As/GaAs quantum dots. [125,176], optically detected electron spin resonance [177], and time-resolved photoluminescence [178,179]; the data point at 10 14 cm −3 of Ref. [125] is measured in a 0.1 µm thick buffer layer of a GaAs/AlGaAs stack.…”