Interface-sensitive nuclear magnetic resonance at a semiconductor heterojunction using hyperpolarization

TL;DR

This paper demonstrates an interface-sensitive NMR technique in a semiconductor heterojunction, utilizing hyperpolarization and lattice distortions to detect signals specifically from the heterojunction region.

Contribution

It introduces a novel method for localizing hyperpolarization at a heterojunction using optical pumping and lattice mismatch-induced distortions.

Findings

Successful detection of heterojunction NMR signals

Hyperpolarization localized at the heterojunction

Suppressed nuclear spin diffusion enhances stability

Abstract

We demonstrate an interface-sensitive NMR in a semiconducting nanostructure, where an NMR signal from the minute heterojunction region of a model heterojunction structure (In$_{0.48}$Ga$_{0.52}$P/GaAs) is detected by using nuclear hyperpolarization created by optical pumping. The key to the detection is the use of minute lattice distortions occurring at the heterojunction due to the lattice mismatch, which enables us to create and localize hyperpolarization at the heterojunction and distinguish it from the other parts. In particular, the suppression of nuclear spin diffusion by the spatial variation in the strain and the resultant unexpectedly stable hyperpolarization at the heterojunction are the keys to successful detection.