Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 18: Spindependent Transport II
MA 18.11: Vortrag
Mittwoch, 28. März 2007, 17:45–18:00, H22
Interplay of multiferroic behaviour, electronic phase separation and colossal resistance effects in Pr1−xCaxMnO3 — •C. Jooss1, S. Schramm1, P. Moschkau1, J. Hoffmann1, L. Wu2, T. Beetz2, R. Klie2, M. Beleggia2, and Y. Zhu2 — 1Institut für Materialphysik, Univ. Göttingen, Friedrich Hund Platz 1, 37077 Göttingen — 2Brookhaven National Laboratory, Upton NY 11973, USA
Pr1−xCaxMnO3 in the doping range between 0.3 < x < 0.5 represent an extremely interesting manganite system for the study of the interplay of different kinds of ordering (charge, orbital, lattice and spin) and the related drastic changes of the transport properties. TEM reveals the presence of electronic and structural phase separation in the chemically homogeneous material between a Zener polaron orbital and charge ordered and disordered phase in a broad temperature and doping regime. The Zener polaron (ZP) type ordering is additionally confirmed by atomic resolution EELS measurements. The ratio of the ZP ordered and disordered phases strongly depend on temperature. The ZP-ordered phase is multiferroic, showing anitferromagnetic order and weak ferroelectric polarisation due to a non-centrosymmetric distortion of the MnO6 octahedra involved in the ZP. In-situ TEM imaging with applied electric currents, we show that local ZP- and charge-ordered domains can be set into motion, be dissolved and re-formed by an electric current. This represents a common mechanism for the resistance change at low and room temperatures. In addition, the CMR effect will be analyzed in the background of the determined ordered structure.