Resonant optical cooling of nuclear spins in case of strong Knight field of photoexcited electrons

TL;DR

This paper presents a theoretical study of resonant nuclear spin cooling in semiconductors, showing how strong Knight fields can significantly alter magnetic-field effects like the Hanle effect.

Contribution

It introduces a model for resonant nuclear spin cooling considering strong Knight fields, highlighting their impact on magnetic-field dependence of spin polarization.

Findings

Resonant cooling can modify the shape of Hanle curves.

Strong Knight fields influence the Overhauser field.

Theoretical predictions align with experimental observations.

Abstract

Resonant cooling of the nuclear spin system of a semiconductor by spin-polarized charge carriers under pumping with helicity-modulated polarized light is considered theoretically. It is shown that in the case of strong Knight field of charge carriers, exceeding local fields of the dipole-dipole interaction of nuclear spins, the Overhauser field arising as a result of resonant cooling can considerably modify the overall shape of magnetic-field dependences of charge carrier spin polarization, experimentally observed as the Hanle effect.