High Field magnetospectroscopy to probe the 1.4eV Ni color center in diamond

TL;DR

This study uses high magnetic field magnetospectroscopy to investigate the electronic structure and symmetry of the 1.4 eV Ni color center in synthetic diamond, revealing its trigonal symmetry and limitations of existing models.

Contribution

It provides detailed experimental data and analysis of the Ni color center's symmetry and electronic configuration, challenging previous crystal field assumptions.

Findings

Ni center has trigonal symmetry aligned along [111]

Effective spin Hamiltonian describes the defect's magnetic properties

Crystal field model has limitations for this defect

Abstract

A magneto-optical study of the 1.4 eV Ni color center in boron-free synthetic diamond, grown at high pressure and high temperature, has been performed in magnetic fields up to 56 T. The data is interpreted using the effective spin Hamiltonian of Nazar\'e, Nevers and Davies [Phys. Rev. B 43, 14196 (1991)] for interstitial Ni$^{+}$ with the electronic configuration $3d^{9}$ and effective spin $S=1/2$. Our results unequivocally demonstrate the trigonal symmetry of the defect which preferentially aligns along the [111] growth direction on the (111) face, but reveal the shortcomings of the crystal field model for this particular defect.