Probing Critical Dynamics in 2D CrSBr via NV Spin Decoherence*

Recently, it has been proposed that critical scaling laws at magnetic phase transitions in materials can be analyzed on the microscopic scale using the decoherence dynamics of a nearby NV spin qubit as a probe [1]. Here, we use coherent NV spin resonance techniques to study critical fluctuations in a 2D layered antiferromagnetic material, CrSBr, interfaced with shallow NV probe spin ensembles. We observe temperature dependent changes in T2* of the NV probe spins consistent with macroscopic scaling of critical fluctuations near the Neel temperature in 2D flakes of CrSBr. Furthermore, we study microscopic variations in critical behavior by imaging NV probe spin decoherence with confocal scanning. Our work demonstrates that NV spin decoherence can be used as a powerful probe of critical behavior in 2D magnetic materials on the microscopic scale.

[1] Machado, F., Demler, E. A., Yao, N. Y. & Chatterjee, S. Quantum Noise Spectroscopy of Dynamical Critical Phenomena. Phys Rev Lett 131, 070801 (2023)