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Direct observation of Jahn-Teller critical dynamics at a charge-order Verwey transition
- Source :
- Phys. Rev. B 104, 235114 (2021)
- Publication Year :
- 2021
-
Abstract
- By means of diffuse and inelastic x-ray scattering (DS,IXS), we probe directly the charge-ordering (CO) dynamics in the Verwey system (NaMn$_3$)Mn$_4$O$_{12}$, where a peculiar quadruple perovskite structure with no oxygen disorder stabilizes a nearly full Mn$^{3+}$/Mn$^{4+}$ static charge order at $T_{\rm CO}$=175 K concomitant to a commensurate structural modulation with propagation vector ${\bf q}_{\rm CO}=(\frac{1}{2},\frac{1}{2},0)$. At $T_{\rm CO}$, the IXS spectra unveil a softening of a 35.3 meV phonon at ${\bf q}_{\rm CO}$. Lattice dynamical calculations enable us to attribute this soft phonon to a A$_g$ mode whose polarization matches the Jahn-Teller-like distortion pattern of the structural modulation. This result demonstrates that the Jahn-Teller instability is the driving force of the CO Verwey transition in (NaMn$_3$)Mn$_4$O$_{12}$, thus elucidating a long-standing controversy regarding the mechanism of this transition observed in other mixed-valence systems like magnetite.
- Subjects :
- Condensed Matter - Strongly Correlated Electrons
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 104, 235114 (2021)
- Publication Type :
- Report
- Accession number :
- edsarx.2112.04485
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.104.235114