Examination of Charge Order in Mixed Valence Oxide LuFe2O4 by Mössbauer Quadrupole Effect

2021 ◽  
Vol 90 (6) ◽  
pp. 064702
Author(s):  
Shin Nakamura ◽  
Takuro Katsufuji
Keyword(s):  
Mixed Valence ◽  
Charge Order ◽  
Quadrupole Effect

Correlating conduction properties with the molecular symmetry: segregation of Z and E isomers in the charge-assisted, halogen-bonded cocrystal [(Z,E)-Me2I2TTF]2Br

2016 ◽  
Vol 52 (2) ◽  
pp. 308-311 ◽  
Author(s):  
Olivier Jeannin ◽  
Enric Canadell ◽  
Pascale Auban-Senzier ◽  
Marc Fourmigué
Keyword(s):  
Mixed Valence ◽  
Charge Order ◽  
Halogen Bonding ◽  
Molecular Symmetry ◽  
Conduction Properties

Co-crystallization of theZandEisomers of Me2I2TTF in a mixed-valence bromide salt leads to segregated stacks with two different charge order patterns and associated charge-assisted halogen bonding.

scholarly journals Superlattice-induced ferroelectricity in charge-ordered La1/3Sr2/3FeO3

2019 ◽  
Vol 116 (48) ◽  
pp. 23972-23976 ◽  
Author(s):  
Se Young Park ◽  
Karin M. Rabe ◽  
Jeffrey B. Neaton
Keyword(s):  
Solid Solution ◽  
High Frequency ◽  
Density Functional ◽  
Mixed Valence ◽  
Functional Materials ◽  
Charge Order ◽  
Charge Ordering ◽  
Solid Solution Phase ◽  
Functional Theory ◽  
A Site

Charge-order–driven ferroelectrics are an emerging class of functional materials, distinct from conventional ferroelectrics, where electron-dominated switching can occur at high frequency. Despite their promise, only a few systems exhibiting this behavior have been experimentally realized thus far, motivating the need for new materials. Here, we use density-functional theory to study the effect of artificial structuring on mixed-valence solid-solution La1/3Sr2/3FeO3 (LSFO), a system well studied experimentally. Our calculations show that A-site cation (111)-layered LSFO exhibits a ferroelectric charge-ordered phase in which inversion symmetry is broken by changing the registry of the charge order with respect to the superlattice layering. The phase is energetically degenerate with a ground-state centrosymmetric phase, and the computed switching polarization is 39 μC/cm2, a significant value arising from electron transfer between FeO6 octahedra. Our calculations reveal that artificial structuring of LSFO and other mixed valence oxides with robust charge ordering in the solid solution phase can lead to charge-order–induced ferroelectricity.

scholarly journals Transport anomalies in the layered compound BaPt4Se6

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Sheng Li ◽  
Yichen Zhang ◽  
Hanlin Wu ◽  
Huifei Zhai ◽  
Wenhao Liu ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Mixed Valence ◽  
Charge Order ◽  
Honeycomb Structure ◽  
Layered Compound ◽  
Metallic State ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Dirac Semimetal ◽  
Mixed Valence Compound ◽  
Heat Capacity Measurements

AbstractWe report a layered ternary selenide BaPt4Se6 featuring sesqui-selenide Pt2Se3 layers sandwiched by Ba atoms. The Pt2Se3 layers in this compound can be derived from the Dirac-semimetal PtSe2 phase with Se vacancies that form a honeycomb structure. This structure results in a Pt (VI) and Pt (II) mixed-valence compound with both PtSe6 octahedra and PtSe4 square net coordination configurations. Temperature-dependent electrical transport measurements suggest two distinct anomalies: a resistivity crossover, mimic to the metal-insulator (M-I) transition at ~150 K, and a resistivity plateau at temperatures below 10 K. The resistivity crossover is not associated with any structural, magnetic, or charge order modulated phase transitions. Magnetoresistivity, Hall, and heat capacity measurements concurrently suggest an existing hidden state below 5 K in this system. Angle-resolved photoemission spectroscopy measurements reveal a metallic state and no dramatic reconstruction of the electronic structure up to 200 K.

Heisenberg and double exchange in iron mixed valence [Fe6S6]+ supercluster

1997 ◽  
Vol 90 (3) ◽  
pp. 445-463 ◽  
Author(s):  
M. CZERWINSKI ◽  
J. DĄBROWSKI
Keyword(s):  
Mixed Valence ◽  
Double Exchange

Theory for the mixed-valence state

1979 ◽  
Vol 40 (C5) ◽  
pp. C5-374-C5-374 ◽  
Author(s):  
C. M. Varma
Keyword(s):  
Valence State ◽  
Mixed Valence ◽  
Mixed Valence State
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