Structural, electronic, and magneto-optical properties of YVO${}_3$

Abstract

Optical and magneto-optical properties of YVO${}_3$ 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 YVO${}_3$ 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 ${}^4{A}_{2g}$, ${}^2{E}_g{+}^2{T}_{1g}$, and ${}^2{T}_{2g}$ states. The strong temperature dependence of these bands is in agreement with the formation of orbital order. Despite the small net magnetic moment of 0.01 ${\mu }_B$ per vanadium, the Kerr effect of the order of $0.01^{\circ }$ was observed for all three $d$-bands in the magnetically ordered phase $T_{\text{Neˊel}}<116K$. A surprisingly strong enhancement of the Kerr effect was found below 75 K, reaching a maximum of $0.1^{\circ }$. The effect is ascribed to the non-vanishing net orbital magnetic moment.

Submitted to Phys. Rev. B