Longitudinal spin relaxation in nitrogen-vacancy ensembles in diamond

TL;DR

This study investigates how the longitudinal spin relaxation rate of NV centers in diamond varies with concentration, temperature, and magnetic field, revealing cross-relaxation effects due to dipole-dipole interactions.

Contribution

It provides experimental insights into the dependence of T1 relaxation on NV orientation degeneracy and concentration, highlighting dipole-dipole interactions as a key factor.

Findings

Relaxation rate T1-1 increases with degeneracy of transition frequencies.

Cross-relaxation caused by dipole-dipole interactions is observed.

Temperature and concentration influence the relaxation dynamics.

Abstract

We present an experimental study of the longitudinal electron-spin relaxation of ensembles of negatively charged nitrogen-vacancy (NV ) centers in diamond. The measurements were performed with samples having different NV- concentrations and at different temperatures and magnetic fields. We found that the relaxation rate T1-1 increases when transition frequencies in NV- centers with different orientations become degenerate and interpret this as cross-relaxation caused by dipole-dipole interaction.