Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)
MA 13.39: Poster
Dienstag, 9. März 2004, 15:00–19:00, Bereich A
Spin-polarized tunneling in FM/I/Al junctions based on ferromagnetic oxides — •Stefanie Wagner, Petra Majewski, Mitja Schonecke, Daniel Reisinger, Andreas Erb, Lambert Alff, Matthias Opel, and Rudolf Gross — Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meißner-Str. 8, 85748 Garching
Ferromagnet/insulator/superconductor (FM/I/SC)
junctions are useful to determine the spin polarization of the
charge carriers at the Fermi level in ferromagnetic materials [1].
Due to the Zeeman splitting in the quasiparticle density of states
in superconductors, a non-zero spin polarization in the
ferromagnet leads to an asymmetric tunnelling conductivity.
We have grown high quality thin films of
La2/3Ba1/3MnO3 and Sr2CrWO6 on SrTiO3
substrates using UHV laser-MBE. The structural and magnetic
properties of the films have been determined by x-ray diffraction
and magnetization measurements. The insulating barriers (SiO2,
Al2O3, SrTiO3) with a typical thickness of 2 nm have
been deposited in-situ by UHV laser-MBE or electron beam
evaporation. The surface morphology of both the ferromagnetic
layer and the insulating barrier have been examined in-situ by
atomic force microscopy. Finally, a thin superconducting layer of
Al (Tc = 2.5K) is deposited by electron beam evaporation. After
fabricating small tunnel junctions using optical lithography, we
measure the conductivity across the junctions as a function of
magnetic field at temperatures below 2 K.
[1] P.M. Tedrow and R. Meservey, Phys. Rev. Lett. 26, 191 (1971).