Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3
The quasi-two-dimensional organic charge-transfer salt κ -(BEDT-TTF) 2 Cu 2 (CN) 3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despi...
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MDPI AG
2018-02-01
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| Series: | Crystals |
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| author | Rudra Sekhar Manna Steffi Hartmann Elena Gati John A. Schlueter Mariano de Souza Michael Lang |
| author_facet | Rudra Sekhar Manna Steffi Hartmann Elena Gati John A. Schlueter Mariano de Souza Michael Lang |
| author_sort | Rudra Sekhar Manna |
| collection | DOAJ |
| description | The quasi-two-dimensional organic charge-transfer salt κ -(BEDT-TTF) 2 Cu 2 (CN) 3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material’s low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6 K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material (R. S. Manna et al., Phys. Rev. Lett. 2010, 104, 016403)). A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6 K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures T < 9 K. We tentatively assign the latter effects to B-induced magnetic clusters suspected to nucleate around crystal imperfections. These B-induced effects are absent for the crystals where the 6 K anomaly is most strongly pronounced. The large lattice effects observed at 6 K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters. |
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| institution | Directory Open Access Journal |
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| last_indexed | 2024-04-11T21:47:27Z |
| publishDate | 2018-02-01 |
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| series | Crystals |
| spelling | doaj.art-205235f73cf8446b8664e66d97a1c17b2022-12-22T04:01:23ZengMDPI AGCrystals2073-43522018-02-01828710.3390/cryst8020087cryst8020087Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3Rudra Sekhar Manna0Steffi Hartmann1Elena Gati2John A. Schlueter3Mariano de Souza4Michael Lang5Department of Physics, IIT Tirupati, Tirupati 517506, IndiaPhysics Institute, Goethe University Frankfurt (M), SFB/TR49, D-60438 Frankfurt (M), GermanyPhysics Institute, Goethe University Frankfurt (M), SFB/TR49, D-60438 Frankfurt (M), GermanyDivision of Materials Research, National Science Foundation, Arlington, VA 22230, USAPhysics Institute, Goethe University Frankfurt (M), SFB/TR49, D-60438 Frankfurt (M), GermanyPhysics Institute, Goethe University Frankfurt (M), SFB/TR49, D-60438 Frankfurt (M), GermanyThe quasi-two-dimensional organic charge-transfer salt κ -(BEDT-TTF) 2 Cu 2 (CN) 3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material’s low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6 K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material (R. S. Manna et al., Phys. Rev. Lett. 2010, 104, 016403)). A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6 K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures T < 9 K. We tentatively assign the latter effects to B-induced magnetic clusters suspected to nucleate around crystal imperfections. These B-induced effects are absent for the crystals where the 6 K anomaly is most strongly pronounced. The large lattice effects observed at 6 K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters.http://www.mdpi.com/2073-4352/8/2/87quantum spin liquidsquantum spin frustrationorganic compoundsthermal expansion |
| spellingShingle | Rudra Sekhar Manna Steffi Hartmann Elena Gati John A. Schlueter Mariano de Souza Michael Lang Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 Crystals quantum spin liquids quantum spin frustration organic compounds thermal expansion |
| title | Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 |
| title_full | Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 |
| title_fullStr | Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 |
| title_full_unstemmed | Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 |
| title_short | Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3 |
| title_sort | low temperature lattice effects in the spin liquid candidate κ bedt ttf 2cu2 cn 3 |
| topic | quantum spin liquids quantum spin frustration organic compounds thermal expansion |
| url | http://www.mdpi.com/2073-4352/8/2/87 |
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