Probing of Optically Responsive Paramagnetic Ions via Light-Intensity-Modulated EPR

Abstract

The coupling between the magnetic and optical responses of materials has been a vital topic related with spintronics， optoelectronics and quantum information. As the underlying microscopic factor, spin-optical coupling has been attracting rising attention. A detailed understanding of spin dynamics under laser excitation in relative systems is important for exploiting spin-optical coupling. Here, we employ light intensity modulation (LIM) to dynamically drive the population between spin sublevels via periodic laser excitation, enabling direct detection of spin responses to photoexcitation. Using this approach, we successfully detected spin polarization changes induced by optical modulation in a series of rare-earth doped YAG crystals (Ce, Nd, Er, Yb) and transition-metal (Cr) doped YAG crystals. A multilevel kinetic model was developed to elucidate the dynamic mechanisms governing the spin polarization, yielding theoretical predictions in agreement with experimental results. These findings demonstrate that the LIM technique can serve as a convenient and informative detection method for optically responsive paramagnetic species.