Studying the evolution of exchange and dipolar interactions and spin correlation in vdW magnet CrCl3 across magnetic phases

Abstract

Understanding quantum interactions in van der Waals magnets are critical to realizing their potential for next-generation magnetic, electronic, and spintronic applications. In this study, we investigated the evolution of exchange and dipole-dipole interactions in van der Waals magnet CrCl3 using multifrequency broadband (1-16 GHz) magnetic resonance on a bulk single-crystal CrCl3 sample. We found that the dipolar-broadened low-field resonance linewidth narrows due to exchange narrowing at higher resonance fields. Our findings show that the exchange interaction evolves exponentially as we lower the sample temperature from room temperature to 50 K. However, we found that the dipole-dipole interaction remains constant in the same temperature range. We have also detected the half-field magnetic resonance transition at room temperature, indicating a robust dipole-dipole interaction among spins. The measured inter-spin distance is 2.4(3) A at room temperature. The evolution of dipole interactions, the observation of half-field magnetic resonance, and the strong exchange interaction indicate short-range ordering/correlation in CrCl3 at temperatures far above the magnetic global ordering temperature. This study also demonstrates the significance and sensitivity of the multifrequency electron spin resonance technique for understanding quantum interactions and magnetic correlations in van der Waals magnetic materials.