2D correlations in the van der Waals ferromagnet CrBr3 using high frequency electron spin resonance spectroscopy

Broadening the knowledge and understanding on the magnetic correlations in van der Waals layered magnets is critical in realizing their potential next-generation magneto-electronic applications. In this study, we employ high-frequency (v = 240 GHz) electron spin resonance (ESR) spectroscopy on plate-like quasi two-dimensional (2D) CrBr3 to gain insight into the magnetic interactions as a function of temperature (4-200 K) and the angle of rotation. We find that the temperature dependence of the ESR linewidth is well described by the Ginzburg-Landau critical model, indicative of the presence of 2D correlations. Furthermore, our findings show that the resonance field follows a (3 cos(2) theta - 1)-like angular dependence, while the linewidth follows a (3 cos(2) theta - 1)(2)-like angular dependence, a behavior indicative of 2D correlations that are likely due to the interaction of the external magnetic field applied during the ESR experiment. This study demonstrates the significance of employing spin sensitive techniques such as ESR to better understand the magnetic correlations in similar van der Waals magnets.