Spin-Phonon Coupling and High Pressure Phase Transitions of RMnO3 (R= Ca and Pr): An Inelastic Neutron Scattering and First Principle Studies

Abstract

We report inelastic neutron scattering measurements over 7-1251 K in CaMnO3 covering various phase transitions, and over 6-150 K in PrMnO3 covering the magnetic transition. The excitations around 20 meV in CaMnO3 and at 17 meV in PrMnO3 are found to be associated with magnetic origin. In spite of similarity of the structure of the two compounds, the neutron inelastic spectrum of PrMnO3 exhibits broad features at 150 K unlike well-defined peaks in the spectrum of CaMnO3. This might result from the difference in nature of interactions in the two compounds (magnetic and Jahn-Teller distortion). The interpretation and analysis of the observed phonon spectra have been performed using ab-initio phonon calculations. We also discuss the effect of pressure on the structural distortions in the orthorhombic phase of CaMnO3 and PrMnO3. On application of pressure, we found that the variations of Mn-O distances are isotropic for CaMnO3 and highly anisotropic for PrMnO3. The calculated structure as a function of pressure in PrMnO3 shows that suppression of Jahn-Teller distortion and insulator to metal transition occurs simultaneously. Our calculations show that this transition may not be associated with the occurrence of the tetragonal phase above 20 GPa as reported in the literature, since the tetragonal phase is found to be dynamically unstable although it is found to be energetically favored over the orthorhombic phase above 20 GPa. CaMnO3 does not show any phase transition up to 60 GPa.

28 Pages, 12 Figures

References in corpus (14)

• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Interplay of Spin-Orbit Interactions, Dimensionality, and Octahedral Rotations in Semimetallic SrIrO${}_3$
• Engineering multiferroism in CaMnO${}_3$
• Magnetic properties of defect-free and oxygen-deficient cubic SrCoO${}_{3-\delta }$
• Tuning ferromagnetism at interfaces between insulating perovskite oxides
• Multiferroic properties of o-LuMnO${}_3$ controlled by b-axis strain
• Determination of the exchange anisotropy in perovskite antiferromagnets using powder inelastic neutron scattering
• Dynamic and structural properties of orthorhombic rare-earth manganites under high pressure
• Magneto- to electro-active transmutation of spin waves in ErMnO3
• Spin-orbital excitation continuum and anomalous electron-phonon interaction in the Mott insulator LaTiO${}_3$
• First-principle calculation of the dielectric and dynamical properties of orthorhombic CaMnO${}_3$
• Spin-Phonon Coupling, High Pressure Phase Transitions and Thermal Expansion of Multiferroic GaFeO3: A Combined First Principles and Inelastic Neutron Scattering Study
• On the Extraction of Exchange Parameters in Transition-Metal Perovskites
• Zone center phonons of the orthorhombic RMnO3 (R = Pr, Eu, Tb, Dy, Ho) perovskites

Cited by in corpus (3)

• Electron-polaron dichotomy of charge carriers in perovskite oxides
• Interplay between trimer structure and magnetic ground state in Ba5Ru3O12 probed by Neutron and muSR techniques
• Lattice and magnetic dynamics in YVO${}_3$ Mott insulator studied by neutron scattering and first-principles calculations