Large two-level magnetoresistance effect in doped manganite grain   boundary junctions
  We performed a systematic analysis of the tunneling magnetoresistance (TMR) effect in single grain boundary junctions formed in epitaxial La(2/3)Ca(1/3)MnO(3) films deposited on SrTiO(3) bicrystals. For magnetic fields H applied parallel to the grain boundary barrier, an ideal two-level resistance switching behavior with sharp transitions is observed with a TMR effect of up to 300% at 4.2 K and still above 100% at 77 K. Varying the angle between H and the grain boundary results in differently shaped resistance vs H curves. The observed behavior is explained within a model of magnetic domain pinning at the grain boundary interface. 
J. B. Philipp (2), C. Hoefener (1), S. Thienhaus (1), J. Klein (1), L.   Alff (1 and 2), and R. Gross (2) ((1) II. Physikali...