Orbital Correlations in the Pseudo-cubic O and Rhombohedral R Phase of Undoped LaMnO3

Subsections

• Introduction to manganites
  • Earlier studies
• The colossal magneto-resistive effect
• Physics of manganites
  • Crystal field effect
  • Jahn-Teller distortion
  • Double exchange mechanism
  • Semi-covalent exchange and the Goodenough-Kanamori rule
  • Summary
• Phase diagram of La_1-xCa_xMnO₃ as an example
• Introduction to the question: high temperature phases of the undoped LaMnO₃
• Experimental methods
  • Sample preparation
  • Differential thermal analysis
  • Neutron powder diffraction
  • Obtaining experimental PDFs
  • Real space PDF refinement
  • Reciprocal space Rietveld refinement
  • Model independent peak analysis
• Local structure from PDF analysis
• Average structure from the PDF and Rietveld analysis
  • Crystallographic phase determination
  • Lattice structure parameters
  • Summary
• Intermediate structure from PDF analysis
• Discussion and conclusions