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arXiv · 2111.11770

Excited State Spectroscopy of Boron Vacancy Defects in Hexagonal Boron Nitride using Time-Resolved Optically Detected Magnetic Resonance

Simon Baber·Ralph N. E. Malein·Prince Khatri·Paul S. Keatley·Shi Guo·Freddie Withers·Andrew J. Ramsay·Isaac J. Luxmoore
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Abstract

We report optically detected magnetic resonance (ODMR) measurements of an ensemble of spin-1 negatively charged boron vacancies in hexagonal boron nitride. The photoluminescence decay rates are spin-dependent, with inter-system crossing rates of $1.02~\mathrm{ns^{-1}}$ and $2.03~\mathrm{ns^{-1}}$ for the $m_s=0$ and $m_s=\pm 1$ states, respectively. Time-gating the photoluminescence enhances the ODMR contrast by discriminating between different decay rates. This is particularly effective for detecting the spin of the optically excited state, where a zero-field splitting of $\vert D_{ES}\vert=2.09~\mathrm{GHz}$ is measured. The magnetic field dependence of the time-gated photoluminescence exhibits dips corresponding to the Ground (GSLAC) and excited-state (ESLAC) anti-crossings. Additional dips corresponding to anti-crossings with nearby spin-1/2 parasitic impurities are also observed. The ESLAC dip is sensitive to the angle of the external magnetic field. Comparison to a model suggests that the anti-crossings are mediated by the interaction with nuclear spins, and allow an estimate of the ratio of the spin-dependent relaxation rates from the singlet back into the triplet ground state of $\kappa_0/\kappa_1=0.34$. This work provides important spectroscopic signatures of the boron vacancy, and information on the spin pumping and read-out dynamics.

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Simon Baber, Ralph N. E. Malein, Prince Khatri, Paul S. Keatley, Shi Guo, Freddie Withers, Andrew J. Ramsay, Isaac J. Luxmoore. 2021-11-23. Excited State Spectroscopy of Boron Vacancy Defects in Hexagonal Boron Nitride using Time-Resolved Optically Detected Magnetic Resonance. https://doi.org/10.1021/acs.nanolett.1c04366

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