Hf influence on the magnetic behavior of hematite nanoparticles

P. G. BERCOFF; J. CARPENCO; C. HERME; S. E. JACOBO

Buenos Aires

Congreso; At the frontiers of Condensed Matter IV; 2008

In order to study the influence of defects on the memory effect of hematite, Hf-doped hematite was synthesized by the self-combustion method. The obtained nanoparticles of  60 nm were characterized by x ray diffraction (XRD) and magnetometry. Room temperature hysteresis loops show a paramagnetic contribution that slightly increases with Hf content and a very hard ferromagnetic contribution with coercivities which reach 6100 Oe for the sample with higher Hf content. Magnetization vs temperature data indicate that memory is enhanced while the Morin temperature is lowered with the doping, even when the concentration of Hf is as low as 1%. The results are interpreted in terms of the changes in the anisotropy introduced by the defects in the lattice.