High-Frequency Electron Paramagnetic Resonance Properties of Kagome Crystal YMn6Sn6

Kagome magnetic crystals received a great deal of research attention in the recent past for their intriguing magnetic properties. Recently, YMn6Sn6 has been shown to exhibit a number of nontrivial magnetic phases, and the origin remains elusive. We measured EPR/FMR at high fields and frequencies to investigate the local field at the magnetic Mn ions in YMn6Sn6. In particular, we studied the signals at 120 and 240 GHz (4 and 8 cm-1, resp.) We observe the phase transitions and the coexistence of different phases in the transition region, which are approximately in line with the B-T phase diagram for YMn6Sn6. This work underscores the importance of employing the high/multifrequency EPR technique in probing for the microscopic mechanisms to better understand the observed new magnetic phases/textures.