Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature

TL;DR

This study investigates the dynamic polarization and relaxation behaviors of 75As nuclei in silicon at high magnetic fields and low temperatures, revealing effective polarization mechanisms and temperature-dependent relaxation processes.

Contribution

It provides new experimental insights into nuclear polarization and relaxation mechanisms of 75As in silicon under extreme conditions.

Findings

Effective nuclear polarization achieved via Overhauser effect.

Polarization through solid effect by exciting forbidden transitions.

Relaxation rate exhibits strong temperature dependence consistent with Orbach process.

Abstract

We present the results of experiments on dynamic nuclear polarization and relaxation of 75As in silicon crystals. Experiments are performed in strong magnetic fields of 4.6 T and temperatures below 1 K. At these conditions donor electron spins are fully polarized, and the allowed and forbidden ESR transitions are well resolved. We demonstrate effective nuclear polarization of 75As nuclei via the Overhauser effect on the time scale of several hundred seconds. Excitation of the forbidden transitions leads to a polarization through the solid effect. The relaxation rate of donor nuclei has strong temperature dependence characteristic of Orbach process.