title: Direct observation of electronic-liquid-crystal phase transitions and their microscopic origin in La1/3Ca2/3MnO3.
abstract: The ground-state electronic order in doped manganites is frequently associated with a lattice modulation, contributing to their many interesting properties. However, measuring the thermal evolution of the lattice superstructure with reciprocal-space probes alone can lead to ambiguous results with competing interpretations. Here we provide direct observations of the evolution of the superstructure in La1/3Ca2/3MnO3in real space, as well as reciprocal space, using transmission electron microscopic (TEM) techniques. We show that the transitions are the consequence of a proliferation of dislocations plus electronic phase separation. The resulting states are well described by the symmetries associated with electronic-liquid-crystal (ELC) phases. Moreover, our results resolve the long-standing controversy over the origin of the incommensurate superstructure and suggest a new structural model that is consistent with recent theoretical calculations.
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: J
authors.initials: J
authors.lastname: Tao
authors.affiliation: Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: K
authors.initials: K
authors.lastname: Sun
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: W-G
authors.initials: WG
authors.lastname: Yin
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xin
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Wen
authors.affiliation: Department of Physics &Astronomy, Shanghai JiaoTong University, Shanghai, China.
authors.forename: W
authors.initials: W
authors.lastname: Luo
authors.affiliation: Department of Materials Science and Engineering, National University of Singapore, 119077 Singapore.
authors.forename: S J
authors.initials: SJ
authors.lastname: Pennycook
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Tranquada
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu