Observation of charge–transfer–driven antiferroelectricity in 3d-pyrochlore multiferroic Cu2OCl2

Wu, Hung-Cheng; Yuan, Jiangyan; Chandrasekhar, K. Devi; Lee, C. H.; Li, W. H.; Wang, Chin-Wei; Chen, J. M.; Lin, Jiunn-Yuan; Berger, H.; Yen, T. W.; Huang, Shin-Ming; Chu, C. W.; Yang, H. D.

doi:10.1016/j.mtphys.2018.12.003

Cited by 17 publications

(14 citation statements)

References 35 publications

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“…Though AFE compounds are also of fundamental interest and can possess similar advantages as their magnetic counterparts, this type of order is much less explored due to conceptual difficulties in defining the basic criteria of antiferroelectricity and identifying its unique experimental signatures. Besides studies on model-type perovskite antiferroelectrics [6][7][8][9][10] and antiferroelectricity in liquid crystals [11], there are only few reports on AFE order in other material classes [12][13][14][15][16][17][18].…”

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confidence: 99%

Cooperative Cluster Jahn-Teller Effect as a Possible Route to Antiferroelectricity

et al. 2021

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confidence: 99%

Cooperative Cluster Jahn-Teller Effect as a Possible Route to Antiferroelectricity

et al. 2021

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“…Cu 2 OCl 2 is an example of the pyrochlore having the centrosymmetric nonpolar space group Fddd . Its structure belongs to a pyrochlore-like corner-shared tetrahedral network. , The structural formula of this substance is Cu 16d 2 □ 16c 2 □ 16e 2 Cl 16g 2 □ 16f 2 O 8b . It may be obtained from the theoretical structural formula, if we assume that the Wyckoff positions 16 c , 16 e , and 16 f are vacant.…”

Section: Resultsmentioning

confidence: 99%

“…The compounds with general formula A 2 B 2 X 6 Y (where A and B are metal atoms and X and Y are anions), which is isostructural to the mineral pyrochlore NaCa(Nb,Ta) 2 O 6 (OH/F), form a numerous and diverse family of crystalline materials. − Pyrochlore and pyrohlore-like compounds exhibit a great variety of intriguing physical and chemical properties, as well as unique electronic structural states: spin ice (Dy 2 Ti 2 O 7 , Ho 2 Ti 2 O 7 , A 2 Sn 2 O 7 , where A = Pr, Dy, and Ho; “stuffed” spin ice Ho 2+ x Ti 2– x O 7 ), spin glass (Y 2 Mo 2 O 7 , Tb 2 Mo 2 O 7 ), and spin liquid (A 2 Ti 2 O 7 , where A = Tb, Yb, Er, Pr) behaviors, − topological and magnon Hall effects, metal–insulator transition, − colossal magnetoresistance, , ferroelectricity, , metallic “ferroelectricity” or multipolar nematic phase, quantum paraelectric behavior, giant analogous Dirac string and magnetic monopoles, , superconductivity, − large temperature-independent dielectric constant, multiferroism, catalytic activity, , ionic conduction, − and many others. Materials based on the pyrochlore structure have found many technologically important applications, such as luminescence, , nuclear waste immobilization, high-temperature thermal barrier coatings, solid oxide fuel cells, , electronic devices, − etc.…”

Section: Introductionmentioning

confidence: 99%

Structural Diversity of Ordered Pyrochlores

Таланов

2021

Chem. Mater.

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Pyrochlores belong to a numerous family of crystalline materials with a rich variety of technologically important functional properties and developed structural diversity of possible transformations including isosymmetric, reconstructive, and phase transitions of second order (and first order close to second order). Here, using a combination of group-theoretical and crystallographic analysis, we report a uniform classification of 343 types of possible ordered phases, which are theoretically derived from only one initial A 2 B 2 X 6 Y pyrochlore structure by different specific physical mechanisms (order parameters or its combinations) and show a hierarchical relationship between them. A symmetry analysis of the intrinsic relationships between structural degrees of freedom and atomic order in pyrochlore crystals made it possible to highlight six nominal classes of atomic order depending on the ordered sublattice, and by taking into account the role of the improper ordered parameters, only four classes remain: X, XY, ABX, and ABXY. For each of these abstract classes of atomic order the modified Barnighausen tree, illustrating the symmetry pathways of group−subgroup relation and participation of relevant order parameters, was constructed. Three fundamental structural features of the ordered pyrochlores have been established: (a) the impossibility of "pure" (not accompanied by atomic displacements) cation ordering at the A and B pyrochlore sublattices (16d and 16c Wyckoff positions, respectively); (b) the impossibility of "pure" ordering of anions at the X sublattice (48f Wyckoff position); (c) atomic ordering in the A sublattice which is always accompanied by atomic ordering in the B sublattice. A brief review of experimentally known ordered pyrochlores consistent with our structural predictions is given. Finally, the main directions of the theoretical results application including interpretation of the phase transition origins, experimental property predictions, the choice of a model for structural refinement or for materials design as a starting point for energy calculations, and a classification of the hierarchical relationship between phases are discussed. This study provides a symmetry guide for the extensive family of ordered pyrochlores and shows the origin of its structural diversity.

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“…Magnetic susceptibiltity measurements on Cu 2 OCl 2 provided a Néel temperature T N of ∼70 K followed by a broad maximum at ∼140 K [8,9]. Many investigations were carried out to determine the nature of the magnetic order at lower temperatures, leading to several propositions such as an all-in-all-out model [10], an incommensurate spin spiral phase [11], an incommensurate spin cycloidal phase [13] and a collinear antiferromagnetic (AFM) phase [14]. However, only one of these experimental investigations proposed magnetic exchange coupling (J) values extracted from magnetic susceptibility fits [8], which are in disagreement with the reported J values estimated from DFT calculations [15].…”

Section: Magnetic Exchange Interactionsmentioning

confidence: 99%

“…In the first investigation [13], the spin-driven nature of the multiferroicity of Cu 2 OCl 2 was demonstrated, leading to the proposition of a cycloidal non-collinear magnetic order with competing magnetic exchange couplings and driven by an inverse Dzyaloshinskii-Moriya mechanism. In the second article [14], the authors claimed the simultaneous existence, at low temperature, of a collinear antiferromagnetic order and an antiferroelectric phase resulting from a Cl→O charge transfer.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Chemical Pressure on the Magnetic Properties of the Mixed Anion Cuprates Cu2OX2 (X = Cl, Br, I)

Lafargue‐Dit‐Hauret

Rocquefelte

2022

Computation

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In this study, we theoretically investigate the structural, electronic and magnetic properties of the Cu2OX2 (X = Cl, Br, I) compounds. Previous studies reported potential spin-driven ferroelectricity in Cu2OCl2, originating from a non-collinear magnetic phase existing below TN∼70 K. However, the nature of this low-temperature magnetic phase is still under debate. Here, we focus on the calculation of J exchange couplings and enhance knowledge in the field by (i) characterizing the low-temperature magnetic order for Cu2OCl2 and (ii) evaluating the impact of the chemical pressure on the magnetic interactions, which leads us to consider the two new phases Cu2OBr2 and Cu2OI2. Our ab initio simulations notably demonstrate the coexistence of strong antiferromagnetic and ferromagnetic interactions, leading to spin frustration. The TN Néel temperatures were estimated on the basis of a quasi-1D AFM model using the abinitioJ couplings. It nicely reproduces the TN value for Cu2OCl2 and allows us to predict an increase of TN under chemical pressure, with TN = 120 K for the dynamically stable phase Cu2OBr2. This investigation suggests that chemical pressure is an effective key factor to open the door of room-temperature multiferroicity.

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Observation of charge–transfer–driven antiferroelectricity in 3d-pyrochlore multiferroic Cu2OCl2

Cited by 17 publications

References 35 publications

Cooperative Cluster Jahn-Teller Effect as a Possible Route to Antiferroelectricity

Cooperative Cluster Jahn-Teller Effect as a Possible Route to Antiferroelectricity

Structural Diversity of Ordered Pyrochlores

Influence of the Chemical Pressure on the Magnetic Properties of the Mixed Anion Cuprates Cu2OX2 (X = Cl, Br, I)

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