Crystal field splitting and magnetic behavior of Nd2BaCuO5 single crystals

Single crystals of Nd2BaCuO5 oxide have been prepared starting from the powder oxide, and x-ray structural determination and magnetic studies have been carried out. Nd2BaCuO5 crystallizes with tetragonal symmetry, space group P4/mbm. The temperature dependence of the magnetic susceptibility measured along the c axis shows a net maximum at 7.5 K, indicative of the presence of an antiferromagnetic ordering below that temperature. This behavior has been confirmed by specific heat measurements, which show a lambda transition at 7.8 K. However, the magnetic susceptibility measured along the a axis does not show any maximum. This anisotropy has been explained as the result of the crystal field effect associated with the Nd3+ ion, by means of the determination of a consistent set of energy levels for the Nd2BaCuO5 oxide and the calculation of the paramagnetic susceptibilities according to the Van Vleck formalism. The rather low antiferromagnetically ordered magnetic moment of the Nd3+ ion, 0.81mu(B), is explained taking into account the calculated anisotropic g values of the crystal ground term of the Nd3+ ion.