High nitrogen-vacancy density diamonds for magnetometry applications

TL;DR

This study demonstrates the production of high-density nitrogen-vacancy diamond samples with optimized properties for magnetometry, achieving record NV concentrations and analyzing their relaxation and sensitivity limits.

Contribution

It introduces a method to produce millimeter-scale diamonds with record NV- densities and characterizes their optical and spin properties for magnetometry applications.

Findings

Highest NV- concentration achieved was 16 ppm.

Effective transverse spin relaxation time T2* was 118 ns.

Projected magnetometer sensitivity is ~150 fT/√Hz.

Abstract

Nitrogen-vacancy (NV) centers in millimeter-scale diamond samples were produced by irradiation and subsequent annealing under varied conditions. The optical and spin relaxation properties of these samples were characterized using confocal microscopy, visible and infrared absorption, and optically detected magnetic resonance. The sample with the highest NV- concentration, approximately 16 ppm = 2.8 x 10^{18} cm^{-3}, was prepared with no observable traces of neutrally-charged vacancy defects. The effective transverse spin relaxation time for this sample was T2* = 118(48) ns, predominately limited by residual paramagnetic nitrogen which was determined to have a concentration of 52(7) ppm. Under ideal conditions, the shot-noise limited sensitivity is projected to be ~150 fT/\sqrt{Hz} for a 100 micron-scale magnetometer based on this sample. Other samples with NV- concentrations from .007 to 12 ppm and effective relaxation times ranging from 27 to 291 ns were prepared and characterized.