Electronic structure and magnetic properties of transition metal diborides

The temperature dependencies of the magnetic susceptibility χχ and its anisotropy Δχ=χ‖−χ⊥ were measured for the hexagonal single crystalline TB2 compounds (T=ScT=Sc, Ti, Zr, Hf, V and Cr) in the temperature range 4.2–300 K. It was found that Δχ varies strongly and nonmonotonously with the filling of the hybridized d-band, being almost temperature independent and the largest for the diborides of group 4 metals. Ab initio calculations of the electronic structure and susceptibility of the diborides provide evidence that magnetic anisotropy originates from competing Van Vleck paramagnetism and the orbital diamagnetism of conduction electrons.