Magnetic properties of R2WO6 (where R = Nd, Sm, Eu, Gd, Dy and Ho)

The magnetic and electrical measurements carried out on the R2WO6 tungstates showed a paramagnetic behaviour for samples with R = Nd, Gd, Dy and Ho and more complex one for samples with R = Sm and Eu in the temperature range 4.2-280 K and an insulating state at room temperature. With increasing atomic number of the R element the Curie-Weiss temperature increases from -43.5 K for Nd2WO6 to -2.7 K for Ho2WO6, excluding Sm2WO6 and Eu2WO6 compounds for that the Curie-Weiss region is not observed and the imaginary part of susceptibility is close to zero. The effective magnetic moment is close to the theoretical one for the free R ion and the magnetic moment measured in magnetic field of 14 T and at temperature of 4.2 K, generally, does not reach the saturation state. The temperature independent residual susceptibility is negative for Nd2WO6 and positive for the remaining compounds suggesting different proportions of the Landau, Pauli and van Vleck contributions to the total susceptibility. An increase of the orbital magnetic contribution to the total magnetic moment is suggested from the fitting of the Lande factor in the compounds under study. (C) 2009 Elsevier B.V. All rights reserved.