Chiral Metallic DM-EDT-TTF Radical Cation Salts: Anion Size-Dependent Structural and Electronic Transitions, Charge Ordering, and Chirality-Induced Spin Selectivity
Both enantiomers (S,S) and (R,R) of the chiral mixed-valence radical cation salts (DM-EDT-TTF)2XO4 (X = Cl or Re) have been prepared by electrocrystallization. Single-crystal high-quality synchrotron radiation data allowed for the very accurate determination of their 298 and 18 K structures. At room...
| Autores: | , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/398780 |
| Acceso en línea: | http://hdl.handle.net/10261/398780 https://api.elsevier.com/content/abstract/scopus_id/105013156743 |
| Access Level: | acceso embargado |
| Palabra clave: | Crystal structure Molecular structure Quantum mechanics Salts Scattering |
| Sumario: | Both enantiomers (S,S) and (R,R) of the chiral mixed-valence radical cation salts (DM-EDT-TTF)2XO4 (X = Cl or Re) have been prepared by electrocrystallization. Single-crystal high-quality synchrotron radiation data allowed for the very accurate determination of their 298 and 18 K structures. At room temperature, they crystallize in the enantiomorphic space groups P6222 and P6422 for the (S,S) and (R,R) enantiomers, respectively, while at 18 K, the structures have been solved in the P62 and P64 space groups, respectively. This symmetry reduction results in a quadrupled unit cell containing four independent donors disordered over two inequivalent positions. In the perrhenate salts, there is strong structural evidence of the occurrence of charge ordering at 18 K as suggested by the alternation of charge-rich and charge-poor donors within the stacks. The easier establishment of charge disproportionation is very likely related to the higher metal-to-insulator transition temperature for perrhenate compared to perchlorate, as observed in the electrical resistance measurements. Spin-polarized DFT band structure calculations support the magnetic ground state of the materials and the activated low-temperature conductivity as a consequence of gap opening. Single-crystal Raman spectroscopy measurements indicate a stronger charge ordering degree at 10 K for the perrhenate than for the perchlorate salts. For the first time in chiral TTF-based conductors, the chirality-induced spin selectivity (CISS) effect is demonstrated through magnetoresistance measurements at room temperature on thin crystals of (DM-EDT-TTF)2ClO4, with a value of up to 30% for CISS-induced magnetoresistance. |
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