Hard-Magnet L10-CoPt Nanoparticles Advance Fuel Cell Catalysis

Structural studies of L10 FePt nanoparticles

We have studied the lattice parameter changes of L10 FePt nanoparticles annealed to near equilibrium as a function of composition by x-ray diffraction. We have found that the ~111! diffraction peak shifts linearly with composition, however, the c parameter mostly changes in the Pt rich compositions and the a parameter mostly changes in the Fe rich compositions with respect to the equiatomic com...

Structure and magnetic properties of L10 CoPt„AgÕMgO,MgO... thin films

Disordered fcc ~face-centered-cubic! @100# fiber-textured CoPt thin films with thicknesses of 20–40 nm were deposited on a nonmagnetic sputtered MgO seed layer with and without a Ag intermediate layer. These were subsequently annealed at 600–750 °C for 5–10 min using rapid thermal annealing ~RTA!. The structural variants were determined to coexist in the in-plane and normal to the plane directi...

Effect of Au spacer layer on L10 phase ordering temperature of CoPt thin films

Growth and Characterization of L10 FePt and CoPt 001 Textured Polycrystalline Thin Films

Thin 001 textured FePt and CoPt polycrystalline films (5 nm) were deposited with an MgO polycrystalline underlayer on an oxidized Si substrate followed by a Rapid Thermal Annealing (RTA) process. Structural analysis indicated the samples to be fully ordered after 10 minutes (min) of RTA at 700 C. The magnetic hysteresis exhibited strong perpendicular anisotropy and a coercivity ( ) between 6 an...

Magneto-Electric Control of Surface Anisotropy and Nucleation Modes in L10-CoPt Thin Films

The interplay between electric field-controlled surface magnetic anisotropy and micromagnetic nucleation modes for L10-CoPt thin films is investigated with density-functional and micromagnetic model calculations. The electric field redistributes electron states near the Fermi level, which has a fairly strong effect on the surface anisotropy, but due to inversion symmetry, the net anisotropy of ...