Careful first-principles density functional calculations revealed the importance of hexagonal versus cubic stacking of close-packed planes of Pd as far as local magnetic properties were concerned. It was found that, unlike the stable face-centered-cubic phase, which was paramagnetic, the hexagonal-close-packed phase of Pd was ferromagnetic with a magnetic moment of 0.35μB∕atom. The results showed that 2-dimensional defects with local hexagonal close-packed stacking, like twin boundaries and stacking faults, in the otherwise face-centered cubic Pd structure, increased the magnetic susceptibility. The (111) surface also increased the magnetic susceptibility and it became ferromagnetic in combination with an individual stacking fault or twin boundary close to it. On the contrary, it was found that the (100) surface decreased the tendency to ferromagnetism. The results were consistent with the magnetic moment recently observed in small Pd nanoparticles, with a large surface area and a high concentration of 2-dimensional stacking defects.

Magnetism of Two-Dimensional Defects in Pd - Stacking Faults, Twin Boundaries and Surfaces. S.S.Alexandre, E.Anglada, J.M.Soler, F.Yndurain: Physical Review B, 2006, 74[5], 054405 (7pp)