Strain effects in perovskite manganites Anthony Arulraj a, * , Robert E. Dinnebier b , Stefan Carlson c , Michael Hanfland d , Sander van Smaalen a a Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth, Germany b Max Planck Institute for Solid State Research, Heisenbergstrabe 1, D-70569 Stuttgart, Germany c MAX-lab, Lund University, P.O. Box 118, SE-22100 Lund, Sweden d European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex 9, France Abstract Colossal magnetoresistance (CMR) e the dramatic reduction of electrical resistivity in a magnetic field e and charge ordering (CO) in rare earth manganites of the type Ln 1x A x MnO 3 [Ln: rare earth, A: divalent cation] are manifestations of the intricate relation between orbital, spin, charge and lattice degrees of free- dom. Recent studies indicate that the inhomogeneous state of mixed-valence manganites e evidenced by the presence of texture and multiple phase coexistence e is important for the CMR property of manganites. Theoretical models that explain the multiphase coexistence are based on quenched disorder or strain. Here we show that lattice strain due to the JahneTeller (JT) distortions of MnO 6 octahedra and their tilt rotations are not sufficient to provide a unique structureeproperty relation. We present evidence that the science of manganites should take into account shear distortions of the MnO 6 octahedra as well. Pressure evolution of the lattice strain of Nd 0.5 Ca 0.5 MnO 3 shows a minimum around 7 GPa, with the same lattice strain above and below this pressure achieved by shear- and JT-type distortions, respectively. In general, a particular lattice strain of manganites can be achieved by different combinations of JT-type and shear-type distortions of the MnO 6 octahedra, together with their tilts, which suggest a plausible description of the inhomogeneous state in manganites as one where phases with differently distorted states having the same lattice strain are preserved. Ó 2007 Published by Elsevier Ltd. Keywords: Manganites; Lattice distortion; Shear strain; JahneTeller distortion; Perovskites * Corresponding author. Present address: Department of Magnetism, Hahn-Meitner-Institute, Berlin. Tel.: þ49 30 8062 2793; fax: þ49 30 8062 3172. E-mail addresses: anthony.arulraj@uni-bayreuth.de, anthony.arulraj@hmi.de (A. Arulraj). 0079-6786/$ - see front matter Ó 2007 Published by Elsevier Ltd. doi:10.1016/j.progsolidstchem.2007.01.034 Progress in Solid State Chemistry 35 (2007) 367e377 www.elsevier.com/locate/pssc