Excited-state spin-resonance spectroscopy of V$${}_{{{{{{{{\rm{B}}}}}}}}}^{-}$$ defect centers in hexagonal boron nitride
Nikhil Mathur, Arunabh Mukherjee, Xingyu Gao, Jialun Luo, Brendan McCullian, Tongcang Li, A. Nick Vamivakas, Gregory D. Fuchs
Abstract
Abstract The recently discovered spin-active boron vacancy (V $${}_{{{{{{{{\rm{B}}}}}}}}}^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> ) defect center in hexagonal boron nitride (hBN) has high contrast optically-detected magnetic resonance (ODMR) at room-temperature, with a spin-triplet ground-state that shows promise as a quantum sensor. Here we report temperature-dependent ODMR spectroscopy to probe spin within the orbital excited-state. Our experiments determine the excited-state spin Hamiltonian, including a room-temperature zero-field splitting of 2.1 GHz and a g-factor similar to that of the ground-state. We confirm that the resonance is associated with spin rotation in the excited-state using pulsed ODMR measurements, and we observe Zeeman-mediated level anti-crossings in both the orbital ground- and excited-state. Our observation of a single set of excited-state spin-triplet resonance from 10 to 300 K is suggestive of symmetry-lowering of the defect system from D 3 h to C 2 v . Additionally, the excited-state ODMR has strong temperature dependence of both contrast and transverse anisotropy splitting, enabling promising avenues for quantum sensing.