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Halder S, Khan MS, Bert F, Aich P, Meneghini C, Ray S. Probing the Magnetic Ground State of Ba 2YIrO 6: Impact of Nonmagnetic Dopants and Spin-Orbit Coupling. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1766. [PMID: 38673123 PMCID: PMC11051550 DOI: 10.3390/ma17081766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 03/29/2024] [Accepted: 04/06/2024] [Indexed: 04/28/2024]
Abstract
Strong spin-orbit coupling (SOC) in iridates has long been predicted to lead to exotic electronic and magnetic ground states. Ba2YIrO6 (BYIO) has attracted particular attention due to the expectation of a Jeff = 0 state for Ir5+ ions under the jj-coupling scheme. However, controversies surround the actual realization of this state, as finite magnetic moments are consistently observed experimentally. We present a multi-physics study of this system by progressively introducing nonmagnetic Sb5+ ions in place of Ir5+ (Ba2YIr1-ySbyO6, BYISO). Despite similar charge and ionic radii, Sb5+ doping appears highly inhomogeneous, coexisting with a fraction of nearly pure BYIO regions, as confirmed by X-ray diffraction (XRD). This aligns with observations in related compounds. While inhomogeneity creates uncertainty, the doped majority phases offer valuable insights. It is relevant that the inclusion of even small amounts of Sb5+ (10-20%) leads to a rise in magnetization. This strengthens our previous suggestion that magnetic Ir ions form dynamic singlets in BYIO, resulting in a near-nonmagnetic background. The observed moment enhancement with nonmagnetic doping supports the breakdown of these singlets. Furthermore, the magnetization steadily increases with an increasing Sb5+ content, contradicting the anticipated approach towards the Jeff = 0 state with increased SOC due to reduced hopping between Ir5+ ions. This reinforces the presence of individual Ir5+ moments. Overall, our findings suggest that Ba2YIrO6 might not possess sufficiently strong SOC to be solely described within the jj-coupling picture, paving the way for further investigation.
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Affiliation(s)
- Shuvajit Halder
- School of Materials Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India (S.R.)
| | - Md Salman Khan
- School of Materials Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India (S.R.)
| | - Fabrice Bert
- Laboratoire de Physique des Solides, UMR CNRS 8502, Universite Paris-Sud, 91405 Orsay, France
| | - Payel Aich
- Dipartimento di Scienze, University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy;
- LASR3 Surface Analysis Laboratory, University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
| | - Carlo Meneghini
- Dipartimento di Scienze, University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy;
| | - Sugata Ray
- School of Materials Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India (S.R.)
- Technical Research Center, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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2
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Zu L, Qian X, Zhao S, Liang Q, Chen YE, Liu M, Su BJ, Wu KH, Qu L, Duan L, Zhan H, Zhang JY, Li C, Li W, Juang JY, Zhu J, Li D, Yu A, Zhao D. Self-Assembly of Ir-Based Nanosheets with Ordered Interlayer Space for Enhanced Electrocatalytic Water Oxidation. J Am Chem Soc 2022; 144:2208-2217. [PMID: 35099956 DOI: 10.1021/jacs.1c11241] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Iridium (Ir)-based electrocatalysts are widely explored as benchmarks for acidic oxygen evolution reactions (OERs). However, further enhancing their catalytic activity remains challenging due to the difficulty in identifying active species and unfavorable architectures. In this work, we synthesized ultrathin Ir-IrOx/C nanosheets with ordered interlayer space for enhanced OER by a nanoconfined self-assembly strategy, employing block copolymer formed stable end-merged lamellar micelles. The interlayer distance of the prepared Ir-IrOx/C nanosheets was well controlled at ∼20 nm and Ir-IrOx nanoparticles (∼2 nm) were uniformly distributed within the nanosheets. Importantly, the fabricated Ir-IrOx/C electrocatalysts display one of the lowest overpotential (η) of 198 mV at 10 mA cm-2geo during OER in an acid medium, benefiting from their features of mixed-valence states, rich electrophilic oxygen species (O(II-δ)-), and favorable mesostructured architectures. Both experimental and computational results reveal that the mixed valence and O(II-δ)- moieties of the 2D mesoporous Ir-IrOx/C catalysts with a shortened Ir-O(II-δ)- bond (1.91 Å) is the key active species for the enhancement of OER by balancing the adsorption free energy of oxygen-containing intermediates. This strategy thus opens an avenue for designing high performance 2D ordered mesoporous electrocatalysts through a nanoconfined self-assembly strategy for water oxidation and beyond.
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Affiliation(s)
- Lianhai Zu
- Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, iChEM, and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.,ARC Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.,Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Xingyue Qian
- Key Laboratory for Soft Chemistry and Functional Materials, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, China.,Key Laboratory of Advanced Catalytic Materials and Technology, Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Shenlong Zhao
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia
| | - Qinghua Liang
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Yu Emily Chen
- Monash Centre for Electron Microscopy (MCEM), Monash University, Clayton, VIC 3800, Australia
| | - Min Liu
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Bing-Jian Su
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30076, Taiwan
| | - Kuang-Hsu Wu
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30076, Taiwan
| | - Longbing Qu
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Linlin Duan
- Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, iChEM, and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
| | - Hualin Zhan
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Jun-Ye Zhang
- Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, iChEM, and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
| | - Can Li
- Institute of Optoelectronic Materials and Devices, China Jiliang University, Hangzhou 310018, China
| | - Wei Li
- Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, iChEM, and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China
| | - Jenh Yih Juang
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30076, Taiwan
| | - Junwu Zhu
- Key Laboratory for Soft Chemistry and Functional Materials, Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Dan Li
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Aibing Yu
- ARC Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.,Southeast University-Monash University Joint Research Institute, Suzhou 215123, China
| | - Dongyuan Zhao
- Department of Chemistry, Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, iChEM, and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.,ARC Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia
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3
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Takahashi H, Suzuki H, Bertinshaw J, Bette S, Mühle C, Nuss J, Dinnebier R, Yaresko A, Khaliullin G, Gretarsson H, Takayama T, Takagi H, Keimer B. Nonmagnetic J=0 State and Spin-Orbit Excitations in K_{2}RuCl_{6}. PHYSICAL REVIEW LETTERS 2021; 127:227201. [PMID: 34889637 DOI: 10.1103/physrevlett.127.227201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
Spin-orbit Mott insulators composed of t_{2g}^{4} transition metal ions may host excitonic magnetism due to the condensation of spin-orbital J=1 triplons. Prior experiments suggest that the 4d antiferromagnet Ca_{2}RuO_{4} embodies this notion, but a J=0 nonmagnetic state as a basis of the excitonic picture remains to be confirmed. We use Ru L_{3}-edge resonant inelastic x-ray scattering to reveal archetypal J multiplets with a J=0 ground state in the cubic compound K_{2}RuCl_{6}, which are well described within the LS-coupling scheme. This result highlights the critical role of unquenched orbital moments in 4d-electron compounds and calls for investigations of quantum criticality and excitonic magnetism on various crystal lattices.
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Affiliation(s)
- H Takahashi
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
- Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - H Suzuki
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - J Bertinshaw
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - S Bette
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - C Mühle
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - J Nuss
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - R Dinnebier
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - A Yaresko
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - G Khaliullin
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - H Gretarsson
- Deutsches Elektronen-Synchrotron DESY, Notkestrstraße 85, D-22607 Hamburg, Germany
| | - T Takayama
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - H Takagi
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
- Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - B Keimer
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
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Bhowal S, Dasgupta I. Spin-orbit effects in pentavalent iridates: models and materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:453001. [PMID: 34352745 DOI: 10.1088/1361-648x/ac1aed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Spin-orbit effects in heavy 5dtransition metal oxides, in particular, iridates, have received enormous current interest due to the prediction as well as the realization of a plethora of exotic and unconventional magnetic properties. While a bulk of these works are based on tetravalent iridates (d5), where the counter-intuitive insulating state of the rather extended 5dorbitals are explained by invoking strong spin-orbit coupling, the recent quest in iridate research has shifted to the other valencies of Ir, of which pentavalent iridates constitute a notable representative. In contrast to the tetravalent iridates, spin-orbit entangled electrons ind4systems are expected to be confined to theJ= 0 singlet state without any resultant moment or magnetic response. However, it has been recently predicted that, magnetism ind4systems may occur via magnetic condensation of excitations across spin-orbit-coupled states. In reality, the magnetism in Ir5+systems are often quite debatable both from theoretical as well as experimental point of view. Here we provide a comprehensive overview of the spin-orbit coupledd4model systems and its implications in the studied pentavalent iridates. In particular, we review here the current experimental and theoretical understanding of the double perovskite (A2BYIrO6,A= Sr, Ba,B= Y, Sc, Gd), 6H-perovskite (Ba3MIr2O9,M= Zn, Mg, Sr, Ca), post-perovskite (NaIrO3), and hexagonal (Sr3MIrO6) iridates, along with a number of open questions that require future investigation.
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Affiliation(s)
- Sayantika Bhowal
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Indra Dasgupta
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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Mohapatra S, Singh A. Magnetic reorientation transition in a three orbital model for Ca 2RuO 4-interplay of spin-orbit coupling, tetragonal distortion, and Coulomb interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:485805. [PMID: 32759475 DOI: 10.1088/1361-648x/abacad] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Including the orbital off-diagonal spin and charge condensates in the self consistent determination of magnetic order within a realistic three-orbital model for the 4d4compound Ca2RuO4, reveals a host of novel features including strong and anisotropic spin-orbit coupling (SOC) renormalization, coupling of strong orbital magnetic moments to orbital fields, and a magnetic reorientation transition. Highlighting the rich interplay between orbital geometry and overlap, SOC, Coulomb interactions, tetragonal distortion, and staggered octahedral tilting and rotation, our investigation yields a planar antiferromagnetic (AFM) order for moderate tetragonal distortion, with easya-bplane and easybaxis anisotropies, along with small canting of the dominantlyyz,xzorbital moments. With decreasing tetragonal distortion, we find a magnetic reorientation transition from the dominantly planar AFM order to a dominantlycaxis ferromagnetic order with significantxyorbital moment.
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Affiliation(s)
| | - Avinash Singh
- Department of Physics, Indian Institute of Technology, Kanpur - 208016, India
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6
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Anisimov PS, Aust F, Khaliullin G, Daghofer M. Nontrivial Triplon Topology and Triplon Liquid in Kitaev-Heisenberg-type Excitonic Magnets. PHYSICAL REVIEW LETTERS 2019; 122:177201. [PMID: 31107055 DOI: 10.1103/physrevlett.122.177201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/06/2019] [Indexed: 06/09/2023]
Abstract
The combination of strong spin-orbit coupling and correlations, e.g., in ruthenates and iridates, has been proposed as a means to realize quantum materials with nontrivial topological properties. We discuss here Mott insulators where on-site spin-orbit coupling favors a local J_{tot}=0 singlet ground state. We investigate excitations into a low-lying triplet, triplons, and find them to acquire nontrivial band topology in a magnetic field. We also comment on magnetic states resulting from triplon condensation, where we find, in addition to the same ordered phases known from the J_{tot}=1/2 Kitaev-Heisenberg model, a triplon liquid taking the parameter space of Kitaev's spin liquid.
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Affiliation(s)
- Pavel S Anisimov
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Friedemann Aust
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Giniyat Khaliullin
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Maria Daghofer
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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7
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Prasad BE, Doert T, Felser C, Jansen M. On
J
eff
=0 Ground State Iridates(V): Tracking Residual Paramagnetism in New Bi
2
NaIrO
6. Chemistry 2018; 24:16762-16765. [DOI: 10.1002/chem.201804226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Indexed: 11/05/2022]
Affiliation(s)
- Beluvalli E. Prasad
- Max-Planck-Institut für Chemische Physik fester Stoffe Nöthnitzer Str. 40 01187 Dresden Germany
| | - Thomas Doert
- Department of Chemistry and Food Chemistry Technische Universität Dresden 01069 Dresden Germany
| | - Claudia Felser
- Max-Planck-Institut für Chemische Physik fester Stoffe Nöthnitzer Str. 40 01187 Dresden Germany
| | - Martin Jansen
- Max-Planck-Institut für Chemische Physik fester Stoffe Nöthnitzer Str. 40 01187 Dresden Germany
- Max-Planck-Institut für Festkörperforschung 70569 Stuttgart Germany
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