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26 April 2024 |
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Article overview
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Spin-Phonon Coupling and High Pressure Phase Transitions of RMnO3 (R= Ca and Pr): An Inelastic Neutron Scattering and First Principle Studies | | S. K. Mishra
; M. K. Gupta
; R. Mittal
; A. I. Kolesnikov
; S. L. Chaplot
; | | Date: |
21 Oct 2015 | | 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. | | Source: | arXiv, 1510.6210 | | Services: | Forum | Review | PDF | Favorites | |
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