@article{10902/27715,
year = {2022},
url = {https://hdl.handle.net/10902/27715},
abstract = {We use high-pressure resistivity and single crystal x-ray diffraction at ambient and low temperature to investigate the charge ordering phase transition of  CaMn 7 O 12 . We have found that at ambient temperature the Jahn-Teller distortion of the  Mn 3 + O 6  octahedra rapidly decreases above 20 GPa, and vanishes at 28 GPa, when two Mn octahedral sites initially occupied by  Mn 3 +  and  Mn 4 +  become regular and equivalent as the result of a charge delocalization. Such a change correlates with a two orders of magnitude drop in the resistivity and a symmetry increase from the low-pressure rhombohedral R ¯ 3  phase to the cubic Im ¯ 3  structure, the same as one found at ambient pressure above 440 K. This yields the slope of the charge ordering phase boundary of  d T c / d p ? ? 6  K/GPa. This result is further supported by the lack of a structural phase transition up to the maximum measured pressure of 30 GPa when the experiment is performed at 70 K. The satellite reflections of the structural modulation of the multiferroic phase of  CaMn 7 O 12  observed at 70 K were found to hold up to 25 GPa with the structure keeping a constant modulation vector  k = ( 0 0 0.925 )  with pressure. The average structure at 70 K does not show other indications of further phase transition.},
organization = {Y. Li and X. Du from Peking University are greatly acknowledged for growing and providing the CaMn7O12 crystals. D. Spahr and J. König from Goethe University are acknowledged for help with the single-crystal diffraction experiments. M.S. would like to acknowledge the financial support under the DFG-ANR Grant No. WI1232/41-1 and DFG GACR Project No. WI3320/3-1. V.M. and J.R.-F. thank the financial support from the Spanish Ministerio de Ciencia e Innovación (MICINN) for the Beatriz Galindo Program (BG20/000777) and for the Project No. PGC2018-097520- A-I00, respectively. DESY Photon Science is gratefully acknowledged. PETRA III at DESY is a member of the Helmholtz Association (HGF).},
publisher = {American Physical Society},
publisher = {Physical Review B, 2022, 105, 064110},
title = {Pressure-induced charge ordering transition in CaMn7O12},
author = {Stekiel, M. and Girard, A. and Zimmer, D. and Monteseguro Padrón, Virginia and Glazyrin, K. and Pedro del Valle, Imanol de and Bayarjargal, L. and Winkler, B. and Ruiz Fuertes, Javier},
}