We report on the electron paramagnetic resonance (EPR) and optical absorption and fluorescence spectroscopy of YAl3(BO3)4 single crystals doped with 0.2 mol% of trivalent chromium. From EPR we determine that the Cr3+ ions reside in sites of essentially octahedral symmetry with an orthorhombic distortion. The ground state 4A2 splitting is determined to be 2(D2 + 3E2) 1.05 0.04 cm-1, where D and E are fine-structure parameters, and we can attribute this splitting to the combined effect of a low-symmetry distortion and spin-orbit coupling. The g-values and fine-structure parameters D and E of the ground state 4A2 are measured to be gx gy gz = 1.978 0.005, |D| = 0.52 0.02 cm-1 and |E| = 0.010 0.005 cm-1 respectively. From 10 K optical absorption we have measured the position and crystal-field splittings of the 2E, 2T1, 4T2, 2T2 and 4T1 states with the 4T2 and 4T1 levels appearing as vibronically broadened bands.
- electron paramagnetic resonance
- optical absorption
- fluorescence spectroscopy