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The honeycomb and hyperhoneycomb polymorphs of IrI3. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Loidl A, Lunkenheimer P, Tsurkan V. On the proximate Kitaev quantum-spin liquid α-RuCl 3: thermodynamics, excitations and continua. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:443004. [PMID: 34371492 DOI: 10.1088/1361-648x/ac1bcf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
This topical review provides an overview over recent thermodynamic, infrared, and THz results on the proximate Kitaev spin-liquid. Quantum-spin liquids are exotic phases characterized by the absence of magnetic ordering even at the lowest temperatures and by the occurrence of fractionalized spin excitations. Among those, Kitaev spin liquids are most fascinating as they belong to the rare class of model systems, that can be solved analytically by decomposing localized spinsS= 1/2 into Majorana fermions. The main aim of this review is to summarize experimental evidence obtained by THz spectroscopy and utilizing heat-capacity experiments, which point to the existence of fractionalized excitations in the spin-liquid state, which in α-RuCl3exists at temperatures just above the onset of magnetic order or at in-plane magnetic fields just beyond the quantum-critical point where antiferromagnetic order becomes suppressed. Thermodynamic and spectroscopic results are compared to theoretical predictions and model calculations. In addition, we document recent progress in elucidating the sub-gap (<1 eV) electronic structure of the 4d5ruthenium electrons to characterize their local electronic configuration. The on-site excitation spectra of thedelectrons below the optical gap can be consistently explained using a spin-orbit coupling constant of ∼170 meV and the concept of multiple spin-orbital excitations. Furthermore, we discuss the phonon spectra of the title compound including rigid-plane shear and compression modes of the single molecular layers. In recent theoretical concepts it has been shown that phonons can couple to Majorana fermions and may play a substantial role in establishing the half-integer thermal quantum Hall effect observed in this material.
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Affiliation(s)
- A Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - P Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - V Tsurkan
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
- Institute of Applied Physics, Chisinau MD-2028, Moldova
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Bergeron H, Lebedev D, Hersam MC. Polymorphism in Post-Dichalcogenide Two-Dimensional Materials. Chem Rev 2021; 121:2713-2775. [PMID: 33555868 DOI: 10.1021/acs.chemrev.0c00933] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Two-dimensional (2D) materials exhibit a wide range of atomic structures, compositions, and associated versatility of properties. Furthermore, for a given composition, a variety of different crystal structures (i.e., polymorphs) can be observed. Polymorphism in 2D materials presents a fertile landscape for designing novel architectures and imparting new functionalities. The objective of this Review is to identify the polymorphs of emerging 2D materials, describe their polymorph-dependent properties, and outline methods used for polymorph control. Since traditional 2D materials (e.g., graphene, hexagonal boron nitride, and transition metal dichalcogenides) have already been studied extensively, the focus here is on polymorphism in post-dichalcogenide 2D materials including group III, IV, and V elemental 2D materials, layered group III, IV, and V metal chalcogenides, and 2D transition metal halides. In addition to providing a comprehensive survey of recent experimental and theoretical literature, this Review identifies the most promising opportunities for future research including how 2D polymorph engineering can provide a pathway to materials by design.
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Affiliation(s)
- Hadallia Bergeron
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Dmitry Lebedev
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.,Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, United States
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Roslova M, Hunger J, Bastien G, Pohl D, Haghighi HM, Wolter AUB, Isaeva A, Schwarz U, Rellinghaus B, Nielsch K, Büchner B, Doert T. Detuning the Honeycomb of the α-RuCl 3 Kitaev Lattice: A Case of Cr 3+ Dopant. Inorg Chem 2019; 58:6659-6668. [PMID: 31045349 DOI: 10.1021/acs.inorgchem.8b03545] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fine-tuning chemistry by doping with transition metals enables new perspectives for exploring Kitaev physics on a two-dimensional (2D) honeycomb lattice of α-RuCl3, which is promising in the field of quantum information protection and quantum computation. The key parameters to vary by doping are both Heisenberg and Kitaev components of the nearest-neighbor exchange interaction between the Jeff = 1/2 Ru3+ spins, depending strongly on the peculiarities of the crystal structure. Here, we present crystal growth by chemical vapor transport and structure elucidation of a solid solution series Ru1- xCr xCl3 (0 ≤ x ≤ 1), with Cr3+ ions coupled to the Ru3+ Kitaev host. The Cr3+ substitution preserves the honeycomb type lattice of α-RuCl3 and creates mixed occupancy of Ru/Cr sites without cationic order within the layers as confirmed by single-crystal X-ray diffraction and transmission electron microscopy investigations. In contrast to high-quality single crystals of α-RuCl3 with ABAB-stacked layers, the ternary compounds demonstrate a significant stacking disorder along the c-axis direction as evidenced by X-ray diffraction and high resolution scanning transmission electron microscopy (HR-STEM). Raman spectra of substituted samples are in line with the symmetry conservation of the parent lattice upon chromium doping. At the same time, our magnetic susceptibility data indicate that the Kitaev physics of α-RuCl3 is increasingly suppressed by the dominant spin-only driven magnetism of Cr3+ ( S = 3/2) in Ru1- xCr xCl3.
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Affiliation(s)
- Maria Roslova
- Faculty of Chemistry and Food Chemistry , Technische Universität Dresden , 01062 Dresden , Germany
| | - Jens Hunger
- Faculty of Chemistry and Food Chemistry , Technische Universität Dresden , 01062 Dresden , Germany
| | - Gaël Bastien
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany
| | - Darius Pohl
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany.,Dresden Center for Nanoanalysis, cfaed , Technische Universität Dresden , 01062 Dresden , Germany
| | - Hossein M Haghighi
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany
| | - Anja U B Wolter
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany
| | - Anna Isaeva
- Faculty of Chemistry and Food Chemistry , Technische Universität Dresden , 01062 Dresden , Germany
| | - Ulrich Schwarz
- Max Planck Institute for Chemical Physics of Solids , 01187 Dresden , Germany
| | - Bernd Rellinghaus
- Dresden Center for Nanoanalysis, cfaed , Technische Universität Dresden , 01062 Dresden , Germany
| | - Kornelius Nielsch
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany
| | - Bernd Büchner
- Institute for Solid State and Materials Research (IFW) Dresden , 01171 Dresden , Germany
| | - Thomas Doert
- Faculty of Chemistry and Food Chemistry , Technische Universität Dresden , 01062 Dresden , Germany
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Reschke S, Mayr F, Widmann S, von Nidda HAK, Tsurkan V, Eremin MV, Do SH, Choi KY, Wang Z, Loidl A. Sub-gap optical response in the Kitaev spin-liquid candidate α-RuCl 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:475604. [PMID: 30398159 DOI: 10.1088/1361-648x/aae805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report detailed optical experiments on the layered compound α-RuCl3 focusing on the THz and sub-gap optical response across the structural phase transition from the monoclinic high-temperature to the rhombohedral low-temperature structure, where the stacking sequence of the molecular layers is changed. This type of phase transition is characteristic for a variety of tri-halides crystallizing in a layered honeycomb-type structure and so far is unique, as the low-temperature phase exhibits the higher symmetry. One motivation is to unravel the microscopic nature of THz and spin-orbital excitations via a study of temperature and symmetry-induced changes. The optical studies are complemented by thermal expansion experiments. We document a number of highly unusual findings: A characteristic two-step hysteresis of the structural phase transition, accompanied by a dramatic change of the reflectivity. A complex dielectric loss spectrum in the THz regime, which could indicate remnants of Kitaev physics. Orbital excitations, which cannot be explained based on recent models, and an electronic excitation, which appears in a narrow temperature range just across the structural phase transition. Despite significant symmetry changes across the monoclinic to rhombohedral phase transition and a change of the stacking sequence, phonon eigenfrequencies and the majority of spin-orbital excitations are not strongly influenced. Obviously, the symmetry of a single molecular layer determines the eigenfrequencies of most of these excitations. Only one mode at THz frequencies, which becomes suppressed in the high-temperature monoclinic phase and one phonon mode experience changes in symmetry and stacking. Finally, from this combined terahertz, far- and mid-infrared study we try to shed some light on the so far unsolved low energy (<1 eV) electronic structure of the ruthenium 4d 5 electrons in α-RuCl3.
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Affiliation(s)
- Stephan Reschke
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
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Winter SM, Tsirlin AA, Daghofer M, van den Brink J, Singh Y, Gegenwart P, Valentí R. Models and materials for generalized Kitaev magnetism. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:493002. [PMID: 28914608 DOI: 10.1088/1361-648x/aa8cf5] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The exactly solvable Kitaev model on the honeycomb lattice has recently received enormous attention linked to the hope of achieving novel spin-liquid states with fractionalized Majorana-like excitations. In this review, we analyze the mechanism proposed by Jackeli and Khaliullin to identify Kitaev materials based on spin-orbital dependent bond interactions and provide a comprehensive overview of its implications in real materials. We set the focus on experimental results and current theoretical understanding of planar honeycomb systems (Na2IrO3, α-Li2IrO3, and α-RuCl3), three-dimensional Kitaev materials (β- and γ-Li2IrO3), and other potential candidates, completing the review with the list of open questions awaiting new insights.
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Affiliation(s)
- Stephen M Winter
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
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Banerjee A, Yan J, Knolle J, Bridges CA, Stone MB, Lumsden MD, Mandrus DG, Tennant DA, Moessner R, Nagler SE. Neutron scattering in the proximate quantum spin liquid α-RuCl
3. Science 2017; 356:1055-1059. [DOI: 10.1126/science.aah6015] [Citation(s) in RCA: 395] [Impact Index Per Article: 56.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 05/16/2017] [Indexed: 01/30/2023]
Affiliation(s)
- Arnab Banerjee
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jiaqiang Yan
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Johannes Knolle
- Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Craig A. Bridges
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Matthew B. Stone
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Mark D. Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - David G. Mandrus
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Department of Materials Science and Engineering, University of Tennesee, Knoxville, TN 37996, USA
| | - David A. Tennant
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Roderich Moessner
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - Stephen E. Nagler
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides. CRYSTALS 2017. [DOI: 10.3390/cryst7050121] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Stolze K, Günther A, Hoffmann HC, Ruck M. Selenium-Rich Octanuclear Iridium Clusters with Mixed-Valent Selenium Ligands in the Densest Known Packing of Ellipsoids. Z Anorg Allg Chem 2014. [DOI: 10.1002/zaac.201300581] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Fehlordnung bei Verbindungen MX3 mit Schichtenstruktur I. Berechnung des Intensitätsverlaufs auf den Streifen der diffusen Röntgenstreuung. Z KRIST-CRYST MATER 2010. [DOI: 10.1524/zkri.1986.176.3-4.233] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
In crystals of compounds MX3 with layer structures, stacking faults are quite common. Assuming close packing for the X atoms, the different types of stacking faults are discussed, including cases in which the M atoms are displaced from the centers of the octahedral voids. Formulae are derived for the calculation of the intensities along the streaks of diffuse scattering. The formulae cover all types of stacking faults when the Reichweite of interaction between layers is s = 1; for s = 2, the cases of hexagonal and cubic close packing of the X atoms are considered.
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Cantow HJ, Hillebrecht H, Magonov SN, Rotter HW, Drechsler M, Thiele G. Abbildung der atomaren und der Überstruktur von α-RuCl3 durch Rastertunnelmikroskopie. Angew Chem Int Ed Engl 1990. [DOI: 10.1002/ange.19901020515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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