Optical and magneto-optical study of orbital and spin ordering transitions in YVO3

Abstract

Optical and magneto-optical properties of YVO3 single crystals have been studied in IR, visible, and UV regions. Below 74K we have observed a large Kerr rotation, comparable to those in ferromagnets. This observation introduces a new class of materials: insulating antiferromagnets with strong magneto-optical Kerr effect, which can have advantages for practical applications. We look into the details of electronic and crystal structure changes. YVO3 was found to undergo two structural phase transitions. Initially, the orthorhombic Pbnm symmetry is lowered below a second-order phase transition at 200K and recovers below 74K at a first-order phase transition. Two Mott–Hubbard (MH) bands dominate the electronic spectrum in the visible range, followed by charge-transfer gap in UV. Below the 200K a transfer of the spectral weight to higher frequencies occurs and a third MH band appears at 3eV. We discuss the results on the basis of spin and orbital ordering theory, proposed for YVO3.