Structural, electronic, and magneto-optical properties of YVO₃

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Optical and magneto-optical properties of YVO₃ single crystal were studied in FIR, visible, and UV regions. Two structural phase transitions at 75 K and 200 K were observed and established to be of the first and second order, respectively. The lattice has an orthorhombic Pbnm symmetry both above 200 K as well as below 75 K, and is found to be dimerized monoclinic Pb11 in between. We identify YVO₃ as a Mott-Hubbard insulator with the optical gap of 1.6 eV. The electronic excitations in the visible spectrum are determined by three d-bands at 1.8, 2.4, and 3.3 eV, followed by the charge-transfer transitions at about 4 eV. The observed structure is in good agreement with LSDA+U band structure calculations. By using ligand field considerations, we assigned these bands to the transitions to the ⁴A₂g, ²Eg + ²T₁g, and ²T₂g states. The strong temperature dependence of these bands is in agreement with the formation of orbital order. Despite the small net magnetic moment of 0.01 μB per vanadium, the Kerr effect of the order of 0.01∘ was observed for all three d-bands in the magnetically ordered phase TNéel<116 K. A surprisingly strong enhancement of the Kerr effect was found below 75 K, reaching a maximum of 0.1∘. The effect is ascribed to the non-vanishing net orbital magnetic moment.