1
|
Yasaka S, Yoshida Y, Tanaka Y, Nakamura Y, Kishida H, Kitagawa H, Maesato M. Electron Localization Induced by Disordered Anions in an Organic Conductor. Inorg Chem 2024; 63:4196-4203. [PMID: 38377386 DOI: 10.1021/acs.inorgchem.3c04226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
We report on a new organic conductor κ″-(ET)2Cu[N(CN)2]Br (κ″-Br), which is the first polymorph of an organic superconductor κ-(ET)2Cu[N(CN)2]Br (κ-Br), where ET denotes bis(ethylenedithio)tetrathiafulvalene. κ″-Br has a similar κ-type arrangement of ET molecules to κ-Br, but, in contrast to the orthorhombic κ-Br, which has ordered polyanion chains, presents a monoclinic crystal structure with disordered polymeric anion chains. To elucidate the electronic state of κ″-Br, we performed band calculations as well as transport, magnetic, and optical measurements. The calculated band dispersion, magnitude of electron correlation, and room-temperature optical conductivity spectra of κ″-Br were comparable to those of κ-Br. Despite these similarities, the κ″-Br salt exhibited a semiconducting behavior. The electron spin resonance and Raman spectroscopies indicated that there is neither magnetic nor charge order in κ″-Br, suggesting the occurrence of Anderson localization due to disordered anion layers.
Collapse
Affiliation(s)
- Soichiro Yasaka
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yukihiro Yoshida
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yuki Tanaka
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yuto Nakamura
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Hideo Kishida
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Hiroshi Kitagawa
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Mitsuhiko Maesato
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| |
Collapse
|
2
|
Kobayashi A, Zhou B, Takagi R, Miyagawa K, Ishibashi S, Kobayashi A, Kawamura T, Nishibori E, Kanoda K. Single-Component Molecular Conductors — Multi-Orbital Correlated π-d Electron Systems. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210230] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Akiko Kobayashi
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156-8550, Japan
| | - Biao Zhou
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156-8550, Japan
| | - Rina Takagi
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
- Institute of Engineering Innovation, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shoji Ishibashi
- Research Center for Computational Design of Advanced Functional Materials (CD-FMat), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Akito Kobayashi
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Taiki Kawamura
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Eiji Nishibori
- Faculty of Pure and Applied Science and Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| |
Collapse
|
3
|
Abstract
This short review article provides the reader with a summary of the history of organic conductors. To retain a neutral and objective point of view regarding the history, background, novelty, and details of each research subject within this field, a thousand references have been cited with full titles and arranged in chronological order. Among the research conducted over ~70 years, topics from the last two decades are discussed in more detail than the rest. Unlike other papers in this issue, this review will help readers to understand the origin of each topic within the field of organic conductors and how they have evolved. Due to the advancements achieved over these 70 years, the field is nearing new horizons. As history is often a reflection of the future, this review is expected to show the future directions of this research field.
Collapse
|
4
|
Urai M, Miyagawa K, Sasaki T, Taniguchi H, Kanoda K. Quantum Disordering of an Antiferromagnetic Order by Quenched Randomness in an Organic Mott Insulator. PHYSICAL REVIEW LETTERS 2020; 124:117204. [PMID: 32242676 DOI: 10.1103/physrevlett.124.117204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
The behavior of interacting spins subject to randomness is a longstanding issue and the emergence of exotic quantum states is among intriguing theoretical predictions. We show how a quantum-disordered phase emerges from a classical antiferromagnet by controlled randomness. ^{1}H NMR of a successively x-ray-irradiated organic Mott insulator finds that the magnetic order collapses into a spin-glass-like state, immediately after a slight amount of disorder centers are created, and evolves to a gapless quantum-disordered state without spin freezing, spin gap, or critical slowing down, as reported by T. Furukawa et al. [Phys. Rev. Lett. 115, 077001 (2015)]PRLTAO0031-900710.1103/PhysRevLett.115.077001 through sequential reductions in the spin freezing temperature and moment.
Collapse
Affiliation(s)
- Mizuki Urai
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Takahiko Sasaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Hiromi Taniguchi
- Department of Physics, Saitama University, Saitama 338-8570, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| |
Collapse
|
5
|
Yamamoto R, Furukawa T, Miyagawa K, Sasaki T, Kanoda K, Itou T. Electronic Griffiths Phase in Disordered Mott-Transition Systems. PHYSICAL REVIEW LETTERS 2020; 124:046404. [PMID: 32058734 DOI: 10.1103/physrevlett.124.046404] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Indexed: 06/10/2023]
Abstract
Solid-state physics and soft-matter physics have been developed independently, with little mutual exchange of the underlying physical concepts. However, after many studies of correlated electron systems, it has been recognized that correlated electrons (especially in Mott-transition systems) in solid matter sometimes show behavior similar to "structured fluids" in soft matter; that is, the electrons exhibit long-length self-organization (but without long-range order) and slow dynamics, which is inevitable for the long-length structures. The essential question is this: what condition causes such behavior in solid matter? We focused on an organic Mott-transition system and demonstrated that the electrons of this system fluctuate very slowly only when the following two factors are met simultaneously: (i) the electronic system is on the metal and Mott-insulator boundary and (ii) the system is subject to quenched disorder. This electronic state with slow dynamics under this condition can be explained by the concept of the "(electronic) Griffiths phase." This concept will potentially be a key in connecting solid-state physics with soft-matter physics.
Collapse
Affiliation(s)
- Riku Yamamoto
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Tetsuya Furukawa
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Takahiko Sasaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Tetsuaki Itou
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| |
Collapse
|
6
|
Abstract
A new superconducting field-effect transistor (FET) in the vicinity of bandwidth-controlled Mott transition was developed using molecular strongly correlated system κ-(BEDT-TTF)2Cu[N(CN)2]Br [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] laminated on CaF2 substrate. This device exhibited significant cooling-rate dependence of resistance below about 80 K, associated with glass transition of terminal ethylene group of BEDT-TTF molecule, where more rapid cooling through glass transition temperature leads to the decrease in bandwidth. We demonstrated that the FET properties such as ON/OFF ratio and polarity can be controlled by utilizing cooling rate. Our result may give a novel insight into the design of molecule-based functional devices.
Collapse
|
7
|
Barman H, Laad MS, Hassan SR. Can disorder act as a chemical pressure? An optical study of the Hubbard model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:195603. [PMID: 29595521 DOI: 10.1088/1361-648x/aabaa1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The optical properties have been studied using the dynamical mean-field theory on a disordered Hubbard model. Despite the fact that disorder turns a metal to an insulator in high dimensional correlated materials, we notice that it can enhance certain metallic behavior as if a chemical pressure is applied to the system resulting in an increase of the effective lattice bandwidth (BW). We study optical properties in such a scenario and compare results with experiments where the BW is changed through isovalent chemical substitution (keeping electron filling unaltered) and obtain remarkable similarities vindicating our claim. We also make the point that these similarities differ from some other forms of BW tuned optical effects.
Collapse
Affiliation(s)
- H Barman
- Institute of Mathematical Sciences, Taramani, Chennai 600113, India
| | | | | |
Collapse
|
8
|
Low-Frequency Dynamics of Strongly Correlated Electrons in (BEDT-TTF)2X Studied by Fluctuation Spectroscopy. CRYSTALS 2018. [DOI: 10.3390/cryst8040166] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Fluctuation spectroscopy measurements of quasi-two-dimensional organic charge-transfer salts (BEDT-TTF) 2 X are reviewed. In the past decade, the method has served as a new approach for studying the low-frequency dynamics of strongly correlated charge carriers in these materials. We review some basic aspects of electronic fluctuations in solids, and give an overview of selected problems where the analysis of 1 / f -type fluctuations and the corresponding slow dynamics provide a better understanding of the underlying physics. These examples are related to (1) an inhomogeneous current distribution due to phase separation and/or a percolative transition; (2) slow dynamics due to a glassy freezing either of structural degrees of freedom coupling to the electronic properties or (3) of the electrons themselves, e.g., when residing on a highly-frustrated crystal lattice, where slow and heterogeneous dynamics are key experimental properties for the vitrification process of a supercooled charge-liquid. Another example is (4), the near divergence and critical slowing down of charge carrier fluctuations at the finite-temperature critical endpoint of the Mott metal-insulator transition. Here also indications for a glassy freezing and temporal and spatial correlated dynamics are found. Mapping out the region of ergodicity breaking and understanding the influence of disorder on the temporal and spatial correlated fluctuations will be an important realm of future studies, as well as the fluctuation properties deep in the Mott or charge-ordered insulating states providing a connection to relaxor or ordered ferroelectric states studied by dielectric spectroscopy.
Collapse
|
9
|
Effects of Disorder on the Pressure-Induced Mott Transition in κ-(BEDT-TTF)2Cu[N(CN)2]Cl. CRYSTALS 2018. [DOI: 10.3390/cryst8010038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
10
|
Sato Y, Kawasugi Y, Suda M, Yamamoto HM, Kato R. Critical Behavior in Doping-Driven Metal-Insulator Transition on Single-Crystalline Organic Mott-FET. NANO LETTERS 2017; 17:708-714. [PMID: 28038313 DOI: 10.1021/acs.nanolett.6b03817] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present the carrier transport properties in the vicinity of a doping-driven Mott transition observed at a field-effect transistor (FET) channel using a single crystal of the typical two-dimensional organic Mott insulator κ-(BEDT-TTF)2CuN(CN)2Cl (κ-Cl). The FET shows a continuous metal-insulator transition (MIT) as electrostatic doping proceeds. The phase transition appears to involve two-step crossovers, one in Hall measurement and the other in conductivity measurement. The crossover in conductivity occurs around the conductance quantum e2/h, and hence is not associated with "bad metal" behavior, which is in stark contrast to the MIT in half-filled organic Mott insulators or that in doped inorganic Mott insulators. Through in-depth scaling analysis of the conductivity, it is found that the above carrier transport properties in the vicinity of the MIT can be described by a high-temperature Mott quantum critical crossover, which is theoretically argued to be a ubiquitous feature of various types of Mott transitions.
Collapse
Affiliation(s)
| | | | - Masayuki Suda
- RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan
- Research Center for Integrative Molecular System (CIMoS), Institute for Molecular Science , 38 Nishigo-naka, Myodaiji, Okazaki 444-8585, Japan
| | - Hiroshi M Yamamoto
- RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan
- Research Center for Integrative Molecular System (CIMoS), Institute for Molecular Science , 38 Nishigo-naka, Myodaiji, Okazaki 444-8585, Japan
| | - Reizo Kato
- RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan
| |
Collapse
|
11
|
Gati E, Garst M, Manna RS, Tutsch U, Wolf B, Bartosch L, Schubert H, Sasaki T, Schlueter JA, Lang M. Breakdown of Hooke's law of elasticity at the Mott critical endpoint in an organic conductor. SCIENCE ADVANCES 2016; 2:e1601646. [PMID: 27957540 PMCID: PMC5142797 DOI: 10.1126/sciadv.1601646] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/03/2016] [Indexed: 05/27/2023]
Abstract
The Mott metal-insulator transition, a paradigm of strong electron-electron correlations, has been considered as a source of intriguing phenomena. Despite its importance for a wide range of materials, fundamental aspects of the transition, such as its universal properties, are still under debate. We report detailed measurements of relative length changes ΔL/L as a function of continuously controlled helium-gas pressure P for the organic conductor κ-(BEDT-TTF)2Cu[N(CN)2]Cl across the pressure-induced Mott transition. We observe strongly nonlinear variations of ΔL/L with pressure around the Mott critical endpoint, highlighting a breakdown of Hooke's law of elasticity. We assign these nonlinear strain-stress relations to an intimate, nonperturbative coupling of the critical electronic system to the lattice degrees of freedom. Our results are fully consistent with mean-field criticality, predicted for electrons in a compressible lattice with finite shear moduli. We argue that the Mott transition for all systems that are amenable to pressure tuning shows the universal properties of an isostructural solid-solid transition.
Collapse
Affiliation(s)
- Elena Gati
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Markus Garst
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
- Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, 01062 Dresden, Germany
| | - Rudra S. Manna
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Ulrich Tutsch
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Bernd Wolf
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Lorenz Bartosch
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Harald Schubert
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Takahiko Sasaki
- Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
| | - John A. Schlueter
- Division of Materials Research, National Science Foundation, Arlington, VA 22230, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Michael Lang
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| |
Collapse
|
12
|
Ogura S, Idobata Y, Zhou B, Kobayashi A, Takagi R, Miyagawa K, Kanoda K, Kasai H, Nishibori E, Satoko C, Delley B. Antiferromagnetic Ordering in the Single-Component Molecular Conductor [Pd(tmdt)2]. Inorg Chem 2016; 55:7709-16. [PMID: 27419930 DOI: 10.1021/acs.inorgchem.6b01166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Crystals of [Pd(tmdt)2] (tmdt = trimethylenetetrathiafulvalenedithiolate) were prepared in order to investigate their physical properties. The electrical resistivity of [Pd(tmdt)2] was measured on single crystals using two-probe methods and showed that the room-temperature conductivity was 100 S·cm(-1). The resistivity behaviors implied that [Pd(tmdt)2] was a semimetal at approximately room temperature and became narrow-gap semiconducting as the temperature was decreased to the lowest temperature. X-ray structural studies on small single crystals of [Pd(tmdt)2] at temperatures of 20-300 K performed using synchrotron radiation at SPring-8 showed no distinct structural change over this temperature region. However, small anomalies were observed at approximately 100 K. Electron spin resonance (ESR) spectra were measured over the temperature range of 2.7-301 K. The ESR intensity increased as the temperature decreased to 100 K and then decreased linearly as the temperature was further decreased to 50 K, where an abrupt decrease in the intensity was observed. To investigate the magnetic state, (1)H nuclear magnetic resonance (NMR) measurements were performed in the temperature range of 2.5-271 K, revealing broadening below 100 K. The NMR relaxation rate gradually increased below 100 K and formed a broad peak at approximately 50 K, followed by a gradual decrease down to the lowest temperature. These results suggest that most of the sample undergoes the antiferromagnetic transition at approximately 50 K with the magnetic ordering temperatures distributed over a wide range up to 100 K. These electric and magnetic properties of [Pd(tmdt)2] are quite different from those of the single-component molecular (semi)metals [Ni(tmdt)2] and [Pt(tmdt)2], which retain their stable metallic states down to extremely low temperatures. The experimental results and the band structure calculations at the density functional theory level showed that [Pd(tmdt)2] may be an antiferromagnetic Mott insulator with a strong electron correlation.
Collapse
Affiliation(s)
- Satomi Ogura
- Department of Chemistry, College of Humanities and Sciences, Nihon University , Setagaya-ku, Tokyo 156-8550, Japan
| | - Yuki Idobata
- Department of Chemistry, College of Humanities and Sciences, Nihon University , Setagaya-ku, Tokyo 156-8550, Japan
| | - Biao Zhou
- Department of Chemistry, College of Humanities and Sciences, Nihon University , Setagaya-ku, Tokyo 156-8550, Japan
| | - Akiko Kobayashi
- Department of Chemistry, College of Humanities and Sciences, Nihon University , Setagaya-ku, Tokyo 156-8550, Japan
| | - Rina Takagi
- Department of Applied Physics, University of Tokyo , Bunkyo-ku, Tokyo 113-8656, Japan.,Center for Emergent Matter Science (CEMS), RIKEN , Wako-shi, Saitama 351-0198, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo , Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo , Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hidetaka Kasai
- Faculty of Pure and Applied Science, Center for Integrated Research in Fundamental Science and Engineering (CIRFSE), and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba , Tsukuba 305-8571, Japan
| | - Eiji Nishibori
- Faculty of Pure and Applied Science, Center for Integrated Research in Fundamental Science and Engineering (CIRFSE), and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba , Tsukuba 305-8571, Japan
| | - Chikatoshi Satoko
- Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University , Setagaya-ku, Tokyo 156-8550, Japan
| | - Bernard Delley
- Condensed Matter Theory Group, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
13
|
Furukawa T, Miyagawa K, Itou T, Ito M, Taniguchi H, Saito M, Iguchi S, Sasaki T, Kanoda K. Quantum Spin Liquid Emerging from Antiferromagnetic Order by Introducing Disorder. PHYSICAL REVIEW LETTERS 2015; 115:077001. [PMID: 26317741 DOI: 10.1103/physrevlett.115.077001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 06/04/2023]
Abstract
Quantum spin liquids, which are spin versions of quantum matter, have been sought after in systems with geometrical frustration. We show that disorder drives a classical magnet into a quantum spin liquid through conducting NMR experiments on an organic Mott insulator, κ-(ET)_{2}Cu[N(CN)_{2}]Cl. Antiferromagnetic ordering in the pristine crystal, when irradiated by x rays, disappears. Spin freezing, spin gap, and critical slowing down are not observed, but gapless spin excitations emerge, suggesting a novel role of disorder that brings forth a quantum spin liquid from a classical ordered state.
Collapse
Affiliation(s)
- T Furukawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - K Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - T Itou
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - M Ito
- Department of Physics, Saitama University, Saitama 338-8570, Japan
| | - H Taniguchi
- Department of Physics, Saitama University, Saitama 338-8570, Japan
| | - M Saito
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Iguchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Sasaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| |
Collapse
|
14
|
Diehl S, Methfessel T, Tutsch U, Müller J, Lang M, Huth M, Jourdan M, Elmers HJ. Disorder-induced gap in the normal density of states of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:265601. [PMID: 26076168 DOI: 10.1088/0953-8984/27/26/265601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The local density of states (DOS) of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, measured by scanning tunneling spectroscopy on in situ cleaved surfaces, reveals a logarithmic suppression near the Fermi edge persisting above the critical temperature T(c). The experimentally observed suppression of the DOS is in excellent agreement with a soft Hubbard gap as predicted by the Anderson-Hubbard model for systems with disorder. The electronic disorder also explains the diminished coherence peaks of the quasi-particle DOS below T(c).
Collapse
Affiliation(s)
- Sandra Diehl
- Graduate School Materials Science In Mainz, Staudingerweg 9, 55128 Mainz, Germany. Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | | | | | | | | | | | | | | |
Collapse
|