Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces

摘要

Careful first-principles density functional calculations reveal theimportance of hexagonal versus cubic stacking of closed packed planes of Pd asfar as local magnetic properties are concerned. We find that, contrary to thestable face centered cubic phase, which is paramagnetic, the hexagonalclose-packed phase of Pd is ferromagnetic with a magnetic moment of 0.35$\mu_{B}$/atom. Our results show that two-dimensional defects with local hcpstacking, like twin boundaries and stacking faults, in the otherwise fcc Pdstructure, increase the magnetic susceptibility. The (111) surface alsoincreases the magnetic susceptibility and it becomes ferromagnetic incombination with an individual stacking fault or twin boundary close to it. Onthe contrary, we find that the (100) surface decreases the tendency toferromagnetism. The results are consistent with the magnetic moment recentlyobserved in small Pd nanoparticles, with a large surface area and a highconcentration of two-dimensional stacking defects.