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MA: Fachverband Magnetismus
MA 18: Magnetic Thin Films II
MA 18.2: Vortrag
Mittwoch, 24. März 2010, 15:30–15:45, H3
Magnetic and microstructural properties of thin NdFeB based films and nanostructures — •Lars Bommer and Dagmar Goll — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany
The magnetic and microstructural properties of NdFeB and NdFeB/Fe thin films and nanostructures are presented. Samples with Cr buffer and protection layer (minimum thickness: d = 50 nm) have been produced by ion beam sputtering at elevated temperatures (Ts = 700 ∘C) using Al2O3 and MgO (001) single crystal substrates. Films deposited on Al2O3 substrates show c-axis growth in out-of-plane direction down to thicknesses of the NdFeB film of d = 10 nm with coercivities up to µ0Hc = 1 T. The texture of films deposited on MgO (001) substrates is less pronounced and films below d = 20 nm show no hard magnetic behavior. For comparison, films were deposited at room temperature on Al2O3 and MgO (001) followed by post-annealing in Ar atmosphere (Tpa = 525-650 ∘C) leading to coercivities as high as µ0Hc = 1.2 T but with isotropic behavior. By TEM images the grain structure of the NdFeB samples is studied. Bilayers of NdFeB (d = 50 nm) and Fe (d = 0-20 nm) show fully exchange coupled behavior. From the temperature dependence of the coercivity the microstructural parameters of all samples have been determined. Furthermore NdFeB periodical patterns were produced by means of electron beam lithography with dot sizes of 1000 nm and 500 nm, respectively.