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A Database for Crystalline Organic Conductors and Superconductors. CRYSTALS 2022. [DOI: 10.3390/cryst12070919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We present a prototype database for quasi two-dimensional crystalline organic conductors and superconductors based on molecules related to bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF, ET). The database includes crystal structures, calculated electronic structures, and experimentally measured properties such as the superconducting transition temperature and critical magnetic fields. We obtained crystal structures from the Cambridge Structural Database and created a crystal structure analysis algorithm to identify cation molecules and execute tight binding electronic structure calculations. We used manual data entry to encode experimentally measured properties reported in publications. Crystalline organic conductors and superconductors exhibit a wide variety of electronic ground states, particularly those with correlations. We hope that this database will ultimately lead to a better understanding of the fundamental mechanisms of such states.
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Gati E, Xiang L, Bud'ko SL, Canfield PC. Measurements of elastoresistance under pressure by combining in-situ tunable quasi-uniaxial stress with hydrostatic pressure. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:023904. [PMID: 32113408 DOI: 10.1063/1.5139437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/23/2020] [Indexed: 06/10/2023]
Abstract
Uniaxial stress, as well as hydrostatic pressure are often used to tune material properties in condensed matter physics. Here, we present a setup that allows for the study of the combined effects of quasi-uniaxial stress and hydrostatic pressure. Following earlier designs for measurements under finite stress at ambient pressures [e.g., Chu et al., Science 337, 710 (2012)], the present setup utilizes a piezoelectric actuator to change stress in situ inside the piston-cylinder pressure cell. We show that the actuator can be operated over the full temperature (from 30 K up to 260 K) and pressure range (up to ≈2 GPa), resulting in a clear and measurable quasi-uniaxial strain. To demonstrate functionality, measurements of the elastoresistance (i.e., the change of resistance of a sample as a response to quasi-uniaxial strain) under finite hydrostatic pressure on the iron-based compound BaFe2As2 are presented as a proof-of-principle example and discussed in the framework of electronic nematicity. Overall, this work introduces the combination of in situ tunable quasi-uniaxial stress and large (up to ≈2 GPa) hydrostatic pressure as a powerful combination in the study of novel electronic phases. In addition, it also points toward further technical advancements which can be made in the future.
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Affiliation(s)
- Elena Gati
- Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA
| | - Li Xiang
- Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA
| | - Sergey L Bud'ko
- Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA
| | - Paul C Canfield
- Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA
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Schuberth E, Tippmann M, Steinke L, Lausberg S, Steppke A, Brando M, Krellner C, Geibel C, Yu R, Si Q, Steglich F. Emergence of superconductivity in the canonical heavy-electron metal YbRh₂Si₂. Science 2016; 351:485-8. [PMID: 26823424 DOI: 10.1126/science.aaa9733] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 12/16/2015] [Indexed: 11/02/2022]
Abstract
The smooth disappearance of antiferromagnetic order in strongly correlated metals commonly furnishes the development of unconventional superconductivity. The canonical heavy-electron compound YbRh2Si2 seems to represent an apparent exception from this quantum critical paradigm in that it is not a superconductor at temperature T ≥ 10 millikelvin (mK). Here we report magnetic and calorimetric measurements on YbRh2Si2, down to temperatures as low as T ≈ 1 mK. The data reveal the development of nuclear antiferromagnetic order slightly above 2 mK and of heavy-electron superconductivity almost concomitantly with this order. Our results demonstrate that superconductivity in the vicinity of quantum criticality is a general phenomenon.
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Affiliation(s)
- Erwin Schuberth
- Walther Meissner Institut für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften, 85748 Garching, Germany. Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.
| | - Marc Tippmann
- Walther Meissner Institut für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften, 85748 Garching, Germany. Physikdepartment, Technische Universität München, 80333 München, Germany
| | - Lucia Steinke
- Walther Meissner Institut für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften, 85748 Garching, Germany. Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Stefan Lausberg
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Alexander Steppke
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Manuel Brando
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Cornelius Krellner
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany. Physics Institute, University of Frankfurt, 60438 Frankfurt, Germany
| | - Christoph Geibel
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China. Department of Physics and Astronomy, Collaborative Innovation Center of Advanced Microstructures, Shanghai Jiaotong University, Shanghai 200240, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.
| | - Frank Steglich
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany. Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang 310058, China. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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Lunkenheimer P, Müller J, Krohns S, Schrettle F, Loidl A, Hartmann B, Rommel R, de Souza M, Hotta C, Schlueter JA, Lang M. Multiferroicity in an organic charge-transfer salt that is suggestive of electric-dipole-driven magnetism. NATURE MATERIALS 2012; 11:755-758. [PMID: 22886065 DOI: 10.1038/nmat3400] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 07/13/2012] [Indexed: 06/01/2023]
Abstract
Multiferroics, showing simultaneous ordering of electrical and magnetic degrees of freedom, are remarkable materials as seen from both the academic and technological points of view. A prominent mechanism of multiferroicity is the spin-driven ferroelectricity, often found in frustrated antiferromagnets with helical spin order. There, as for conventional ferroelectrics, the electrical dipoles arise from an off-centre displacement of ions. However, recently a different mechanism, namely purely electronic ferroelectricity, where charge order breaks inversion symmetry, has attracted considerable interest. Here we provide evidence for ferroelectricity, accompanied by antiferromagnetic spin order, in a two-dimensional organic charge-transfer salt, thus representing a new class of multiferroics. We propose a charge-order-driven mechanism leading to electronic ferroelectricity in this material. Quite unexpectedly for electronic ferroelectrics, dipolar and spin order arise nearly simultaneously. This can be ascribed to the loss of spin frustration induced by the ferroelectric ordering. Hence, here the spin order is driven by the ferroelectricity, in marked contrast to the spin-driven ferroelectricity in helical magnets.
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