Dual-frequency spin-resonance spectroscopy of diamond nitrogen-vacancy centers in zero magnetic field

Abstract

The methods for controlling spin states of negatively charged nitrogen-vacancy (NV) centers using microwave (MW) or radio frequency (rf) excitation fields for electron spin and nuclear spin transitions are effective in strong magnetic fields where a level anticrossing (LAC) occurs. A LAC can also occur at zero field in the presence of transverse strain or electric fields in the diamond crystal, leading to mixing of the spin states. In this Rapid Communication, we investigate zero-field LAC of NV centers using dual-frequency excitation spectroscopy. Under rf modulation of the spin states, we observe sideband transitions and Autler-Townes splitting in the optically detected magnetic resonance (ODMR) spectra. Numerical simulations show that the splitting originates from a Landau-Zener transition between electron spin $|\ifmmode\pm\else\textpm\fi{}1\ensuremath{\rangle}$ states, which potentially provides a way of manipulating NV center spin states in zero or weak magnetic field.