Magnetic properties of the LaNi1-xWxO3 (0≤x≤0.25) perovskites

Magnetic properties of the LaNi1-xWxOx (0 less than or equal to x less than or equal to 0.25) mixed oxides have been studied from the temperature and magnetic field (H) dependence of the magnetization (ICI) and low-temperature neutron diffraction experiments, The variation of M with temperature shows the presence of weak ferromagnetic interactions with Curie temperatures ranging from 200 to 250 K, These interactions become stronger as x increases and this fact has been interpreted in relation to the progressive electronic localization that takes place in this perovskite-like system, The observed ferromagnetic behavior is confirmed by the hysteresis loops obtained in the M vs H curves at different temperatures, The saturation values are however very low in comparison with the expected ones for Ni2+ or Ni3+, On the other hand, an extra peak in the neutron diffraction experiments for the x = 0.20 phase shows the appearance of an antiferromagnetic ordering, which has been interpreted on the basis of a G-type magnetic mode, Both results can be understood considering antiferromagnetic in character interactions with an important canting of the spin arrangement, giving therefore rise to a weak ferromagnetic component, which has been characterized from magnetization measurements, These results have been summarized in a phase diagram in which the most relevant electronic features of the title system can be visualized. (C) 1997 Academic Press.