Room temperature relaxometry of single nitrogen-vacancy centers in proximity to $α$-RuCl₃ nanoflakes

Investigating spin and charge noise in strongly correlated electron systems is a valuable way to analyze their physical properties and unlock new phases of matter. In this context, nitrogen-vacancy (NV) center-based magnetometry has been proven to be a versatile sensor for various classes of magnetic materials in broad temperature and frequency ranges. Here, we use longitudinal relaxation time T₁ of single NV centers to investigate the spin dynamics of nanometers-thin flakes of $α$-RuCl₃ at room temperature. We observe a significant reduction in the T₁ in the presence of $α$-RuCl₃ in proximity to our NVs, which we attribute to paramagnetic spin noise confined in the 2D hexagonal plane. Furthermore, the T₁ time exhibits an almost linear increase with an applied external magnetic field. We associate this trend with the alteration of spin and charge noise in $α$-RuCl₃ under an external magnetic field. These findings suggest that the influence of the room-temperature spin dynamics of $α$-RuCl₃ on the longitudinal relaxation time of the NV center can be used to gain information on the material itself and the technique to be used on other 2D materials.