Magneto-optic properties of uranium-based compounds

Uranium-based compounds often show interesting magnetic properties and large polar Kerr rotations. Because of this, the wavelength and temperature dependencies of the polar Kerr rotation in several uranium-based compounds, including UMn₂Ge₂, UFe₂, and UGa₂, have been investigated. The Mn moments order ferromagnetically in UMn ₂Ge₂ below 380 K, and while the U moments do not order ferromagnetically until the temperature is below 150 K. The measurements presented here show that the size of the Kerr rotation increases from 0.05°at room temperature to 0.15°when the U moments are ordered. The wavelength dependence of the Kerr rotation between 500 and 1000 nm is rather weak. UGa₂ orders ferromagnetically at 130 K, and a Kerr rotation of 0.2°at 85 K and 632.8 nm can be measured, with the rotation increasing to 0.4°at 1000 nm. UFe₂ orders ferromagnetically at 180 K, and the Kerr rotation (85 K, 632.8 nm) is 0.17°. These magnetic and optical properties are discussed in terms of the electronic states of uranium.