DMTTF-CA revisited: temperature-induced valence and structural instability
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arXiv
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| Format: | Preprint |
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2007
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| author | Ranzieri, Paolo Masino, Matteo Girlando, Alberto Lemee-Cailleau, Marie-Helene |
| author_facet | Ranzieri, Paolo Masino, Matteo Girlando, Alberto Lemee-Cailleau, Marie-Helene |
| contents | We report a detailed spectroscopic investigation of temperature-induced valence and structural instability of the mixed-stack organic charge-transfer (CT) crystal 4,4'-dimethyltetrathiafulvalene-chloranil (DMTTF-CA). DMTTF-CA is a derivative of tetrathiafulvalene-chloranil (TTF-CA), the first CT crystal exhibiting the neutral-ionic transition by lowering temperature. We confirm that DMTTF-CA undergoes a continuous variation of the ionicity on going from room temperature down to $\sim$ 20 K, but remains on the neutral side throughout. The stack dimerization and cell doubling, occurring at 65 K, appear to be the driving forces of the transition and of the valence instability. In a small temperature interval just below the phase transition we detect the coexistence of molecular species with slightly different ionicities. The Peierls mode(s) precursors of the stack dimerization are identified. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_cond_mat_0703716 |
| institution | arXiv |
| publishDate | 2007 |
| record_format | arxiv |
| spellingShingle | DMTTF-CA revisited: temperature-induced valence and structural instability Ranzieri, Paolo Masino, Matteo Girlando, Alberto Lemee-Cailleau, Marie-Helene Materials Science Strongly Correlated Electrons We report a detailed spectroscopic investigation of temperature-induced valence and structural instability of the mixed-stack organic charge-transfer (CT) crystal 4,4'-dimethyltetrathiafulvalene-chloranil (DMTTF-CA). DMTTF-CA is a derivative of tetrathiafulvalene-chloranil (TTF-CA), the first CT crystal exhibiting the neutral-ionic transition by lowering temperature. We confirm that DMTTF-CA undergoes a continuous variation of the ionicity on going from room temperature down to $\sim$ 20 K, but remains on the neutral side throughout. The stack dimerization and cell doubling, occurring at 65 K, appear to be the driving forces of the transition and of the valence instability. In a small temperature interval just below the phase transition we detect the coexistence of molecular species with slightly different ionicities. The Peierls mode(s) precursors of the stack dimerization are identified. |
| title | DMTTF-CA revisited: temperature-induced valence and structural instability |
| topic | Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/cond-mat/0703716 |