Optical and magneto-optical properties of Ni₂MnGa alloy at room temperature

The optical and magneto-optical (equatorial Kerr effect) properties of Ni₂MnGa alloy, as well as the magnetic properties, were measured at room temperature and were calculated by using a scalar-relativistic version of the tight-binding linear muffin-tin-orbital atomic-sphere approximation within the local-spin-density approximation. The magnetic susceptibility shows an abrupt increase at 220 K and stays almost constant until the temperature reaches 380 K. The susceptibility steeply decreases to zero when the temperature is higher than 380 K. The peak positions in the experimental and calculated optical-conductivity spectrum coincide. However, the intensities are drastically different. The experimental real parts (∈_1xy) of the off-diagonal components of the dielectric function present two sharp peaks, one at about 1.9 and the other at 3.2 eV, and a broad shoulder at 3.5 eV; all are identified by the calculations.