Photoinduced Electron Spin Resonance Phenomenon in α ‐Cr 2 O 3 Nanospheres

The photoinduced phenomenon in α ‐Cr 2 O 3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315 K. An X‐band electron‐spin resonance spectrometry was employed to probe the magnetic behavior in α ‐Cr 2 O 3 under an IR illumination in the nanosecond regime. The photoinduced effect on both low and high field ESR signals appears above 280 K and is remarkably enhanced just below Néel temperature T N . Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above T N of crystalline α ‐Cr 2 O 3 . In the antiferromagnetic phase, that is, below T N , the shift of the low field absorption could be attributed to the interaction of the light with specific Cr 3+ ions located in strongly distorted sites correlated to strong ligand‐field effect.