Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br
Thermodynamic investigation by calorimetric measurements of the layered organic superconductors, κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and its partially deuterated compounds of κ-(d[2,2]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and κ-(d[3...
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MDPI AG
2021-12-01
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| Online Access: | https://www.mdpi.com/2073-4352/12/1/2 |
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| author | Yuki Matsumura Shusaku Imajo Satoshi Yamashita Hiroki Akutsu Yasuhiro Nakazawa |
| author_facet | Yuki Matsumura Shusaku Imajo Satoshi Yamashita Hiroki Akutsu Yasuhiro Nakazawa |
| author_sort | Yuki Matsumura |
| collection | DOAJ |
| description | Thermodynamic investigation by calorimetric measurements of the layered organic superconductors, κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and its partially deuterated compounds of κ-(d[2,2]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br, performed in a wide temperature range is reported. The latter two compounds were located near the metal–insulator boundary in the dimer-Mott phase diagram. From the comparison of the temperature dependences of their heat capacities, we indicated that lattice heat capacities of the partially deuterated compounds were larger than that of the pristine compound below about 40 K. This feature probably related to the lattice softening was discussed also by the sound velocity measurement, in which the dip-like structures of the Δ<i>v</i>/<i>v</i> were observed. We also discussed the variation of the electronic heat capacity under magnetic fields. From the heat capacity data at magnetic fields up to 6 T, we evaluated that the normal-state <i>γ</i> value of the partially deuterated compound, κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br, was about 3.1 mJ K<sup>−2</sup> mol<sup>−1</sup>. Under the magnetic fields higher than 3.0 T, we observed that the magnetic-field insulating state was induced due to the instability of the mid-gap electronic state peculiar for the two-dimensional dimer-Mott system. Even though the volume fraction was much reduced, the heat capacity of κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br showed a small hump structure probably related to the strong coupling feature of the superconductivity near the boundary. |
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| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T01:41:17Z |
| publishDate | 2021-12-01 |
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| spelling | doaj.art-5a26da68949d4c8793be6b91c5f705b62023-11-23T13:23:35ZengMDPI AGCrystals2073-43522021-12-01121210.3390/cryst12010002Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]BrYuki Matsumura0Shusaku Imajo1Satoshi Yamashita2Hiroki Akutsu3Yasuhiro Nakazawa4Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, JapanInstitute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, JapanDepartment of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, JapanDepartment of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, JapanDepartment of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, JapanThermodynamic investigation by calorimetric measurements of the layered organic superconductors, κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and its partially deuterated compounds of κ-(d[2,2]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br and κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br, performed in a wide temperature range is reported. The latter two compounds were located near the metal–insulator boundary in the dimer-Mott phase diagram. From the comparison of the temperature dependences of their heat capacities, we indicated that lattice heat capacities of the partially deuterated compounds were larger than that of the pristine compound below about 40 K. This feature probably related to the lattice softening was discussed also by the sound velocity measurement, in which the dip-like structures of the Δ<i>v</i>/<i>v</i> were observed. We also discussed the variation of the electronic heat capacity under magnetic fields. From the heat capacity data at magnetic fields up to 6 T, we evaluated that the normal-state <i>γ</i> value of the partially deuterated compound, κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br, was about 3.1 mJ K<sup>−2</sup> mol<sup>−1</sup>. Under the magnetic fields higher than 3.0 T, we observed that the magnetic-field insulating state was induced due to the instability of the mid-gap electronic state peculiar for the two-dimensional dimer-Mott system. Even though the volume fraction was much reduced, the heat capacity of κ-(d[3,3]-BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br showed a small hump structure probably related to the strong coupling feature of the superconductivity near the boundary.https://www.mdpi.com/2073-4352/12/1/2organic superconductorstrong electron correlationsheat capacityMott transition |
| spellingShingle | Yuki Matsumura Shusaku Imajo Satoshi Yamashita Hiroki Akutsu Yasuhiro Nakazawa Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br Crystals organic superconductor strong electron correlations heat capacity Mott transition |
| title | Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br |
| title_full | Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br |
| title_fullStr | Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br |
| title_full_unstemmed | Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br |
| title_short | Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br |
| title_sort | electronic heat capacity and lattice softening of partially deuterated compounds of κ bedt ttf sub 2 sub cu n cn sub 2 sub br |
| topic | organic superconductor strong electron correlations heat capacity Mott transition |
| url | https://www.mdpi.com/2073-4352/12/1/2 |
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