Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 13: Correlated Electrons: Metal Insulator Transition - Part 1
TT 13.1: Vortrag
Dienstag, 28. März 2006, 11:45–12:00, HSZ 105
Multiple ordering processes and the insulator-metal transition in epitaxial PrCaMnO films — •Christian Jooss1, Peter Moschkau1, Sebastian Schramm1, Christine Borchers1, and Yimei Zhu2 — 1Institute of Materials Physics, University of Goettingen, Germany — 2Brookhaven National Laboratory, Upton NY, USA
Pr1−xCaxMnO3 films 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. Recently, it was suggested [1] that a possible specific kind of bond-centered charge ordered state could give rice to ferroelectric properties of this material. We have investigated epitaxial PrCaMnO films on (001) SrTiO3 substrates grown by pulsed laser deposition. The films exhibit an insulator metal (IM) transition in applied magnetic and electric fields below the charge ordering temperature Tc ≈230 K with resistivity changes of up to seven orders of magnitudes. Furthermore, an electric field induced remanet resistivity change is observed at temperature above Tc. High-resolution transmission electron microscopy reveals the presence of orbital and charge ordering. In the x=0.3 samples the correlation lengths of the charge and orbital ordering domains differs and we observe an inhomogeneous charge ordered ground state. We discuss the relation between structure, different types of ordering and electronic transport properties of this material.
[1] D. V. Efremov, J. van den Brink and D. I. Khomskii, Nature Materials 3 (2004) 853.