Regensburg 2004 – scientific programme
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MA: Magnetismus
MA 22: Spinabh
ängiger Transport I
MA 22.1: Talk
Thursday, March 11, 2004, 12:15–12:30, H22
Imaging tunnel magnetoresistance related to magnetic microdomain distribution along a La2/3Ca1/3MnO3 grain boundary — •Wagenknecht Michael1, Timo Nachtrab1, Markus Turad1, Dieter Koelle1, Reinhold Kleiner1, Jan Boris Philipp2, and Rudolf Gross2 — 1Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany — 2Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meißner Straße 8, D-85748 Garching, Germany
We present electrical transport measurements across an artificial grain boundary in a La2/3Ca1/3MnO3 thin film grown on a 24∘ bicrystal SrTiO3 substrate. In the ferromagnetic-metallic phase below Tc ≈ 220 K the grain boundary acts as a tunneling barrier. Applying an in-plane magnetic field up to 40 mT parallel to the grain boundary we observe several discrete jumps in the magnetoresistance across the barrier. We explain the resistance steps by formation of microdomains along the grain boundary. Using low temperature laser scanning microscopy allows us to image the tunnelling conductance distribution along the grain boundary for the discrete resistance steps. By this we are able to map the fraction of parallel/antiparallel aligned microdomains versus magnetic field and to correlate the domain distribution with the overall resistance across the grain boundary.