  VdW materials are a family of materials ranging from semimetal, semiconductor
to insulator, and their common characteristic is the layered structure. These
features make them widely applied in the fabrication of nano-photonic and
electronic devices, particularly, vdW heterojunctions. HBN is the only layered
material to date that is demonstrated to contain optically-detected electronic
spins, which can benefit the construction of solid qubit and quantum sensor,
etc., especially embedded in the nano-layered-devices. To realize this, Rabi
oscillation is a crucial step. Here, we demonstrate the Rabi oscillation of
V$_\text{B}^-$ spins in hBN. Interestingly, we find the behaviors of the spins
are completely different under the conditions of weak and relatively higher
magnetic field. The former behaves like a single wide peak, but the latter
behaves like multiple narrower peaks (e.g., a clear beat in Ramsey fringes). We
conjecture a strong coupling of the spin with the surrounding nuclear spins,
and the magnetic field can control the nuclear spin bath.
