Optical and magneto-optical properties of YVO3 single crystal were studied in the far-infrared, visible, and ultraviolet regions. Two structural phase transitions at 75 K and 200 K were observed and established to be of 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 either dimerized monoclinic Pb11 or triclinic P (1) over bar in between. We identify YVO3 as a Mott-Hubbard insulator with an optical gap of 1.6 eV. The visible spectrum shows three d-band excitations at 1.8, 2.4, and 3.3 eV, followed by 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 (4)A(2g), E-2(g)+T-2(1g), and T-2(2g) states. The strong temperature dependence of these bands is in agreement with the formation of orbital order. Despite the small net magnetic moment of 0.01mu(B) per vanadium, a Kerr effect of the order of 0.01degrees was observed for all three d bands in the magnetically ordered phase (T-Neel=116 K). A surprisingly strong enhancement of the Kerr effect was found below 75 K, reaching a maximum of 0.1degrees. This effect is ascribed to the nonvanishing net orbital magnetic moment.
|Number of pages||11|
|Journal||Physical Review. B: Condensed Matter and Materials Physics|
|Publication status||Published - Feb-2004|
- BAND THEORY