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Wildman EJ, Lawrence GB, Walsh A, Morita K, Simpson S, Ritter C, Stenning GBG, Arevalo-Lopez AM, Mclaughlin AC. Observation of an exotic insulator to insulator transition upon electron doping the Mott insulator CeMnAsO. Nat Commun 2023; 14:7037. [PMID: 37923745 PMCID: PMC10624918 DOI: 10.1038/s41467-023-42858-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 10/17/2023] [Indexed: 11/06/2023] Open
Abstract
A promising route to discover exotic electronic states in correlated electron systems is to vary the hole or electron doping away from a Mott insulating state. Important examples include quantum criticality and high-temperature superconductivity in cuprates. Here, we report the surprising discovery of a quantum insulating state upon electron doping the Mott insulator CeMnAsO, which emerges below a distinct critical transition temperature, TII. The insulator-insulator transition is accompanied by a significant reduction in electron mobility as well as a colossal Seebeck effect and slow dynamics due to decoupling of the electrons from the lattice phonons. The origin of the transition is tentatively interpreted in terms of many-body localization, which has not been observed previously in a solid-state material.
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Affiliation(s)
- E J Wildman
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, UK
| | - G B Lawrence
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, UK
| | - A Walsh
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - K Morita
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - S Simpson
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, UK
| | - C Ritter
- Institut Laue Langevin, 71 Avenue des Martyrs, BP 156, F-38042, Grenoble, Cedex 9, France
| | - G B G Stenning
- ISIS Experimental Operations Division, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX, UK
| | - A M Arevalo-Lopez
- Université de Lille, CNRS, Centrale Lille, ENSCL, Université d'Artois, UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - A C Mclaughlin
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, UK.
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Hong KH, Arevalo-Lopez AM, Coduri M, McNally GM, Attfield JP. Cation, magnetic, and charge ordering in MnFe 3O 5. J Mater Chem C Mater 2018; 6:3271-3275. [PMID: 30009028 PMCID: PMC6003543 DOI: 10.1039/c8tc00053k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/16/2018] [Indexed: 05/22/2023]
Abstract
The recently-discovered high pressure material MnFe3O5 displays a rich variety of magnetically ordered states on cooling. Fe spins order antiferromagnetically below a Néel transition at 350 K. A second transition at 150 K marks Mn spin order that leads to spin canting of some of the Fe spins and ferrimagnetism. A further transition at 60 K is driven by charge ordering of Fe2+ and Fe3+ over two inequivalent Fe sites, with further canting of all spins. Electrical resistivity measurements reveal semiconducting behaviour in MnFe3O5 with a change in activation energy at 285 K.
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Affiliation(s)
- K H Hong
- Centre for Science at Extreme Conditions and School of Chemistry , University of Edinburgh , Mayfield Road , Edinburgh EH9 3JZ , UK .
| | - A M Arevalo-Lopez
- Univ. Lille , CNRS , Centrale Lille , ENSCL , Univ. Artois , UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide , F-59000 Lille , France
| | - M Coduri
- European Synchrotron Radiation Facility , 71 avenue des Martyrs , Grenoble , 38000 , France
| | - G M McNally
- Centre for Science at Extreme Conditions and School of Chemistry , University of Edinburgh , Mayfield Road , Edinburgh EH9 3JZ , UK .
| | - J P Attfield
- Centre for Science at Extreme Conditions and School of Chemistry , University of Edinburgh , Mayfield Road , Edinburgh EH9 3JZ , UK .
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Abstract
Gentle oxidation of lithium titanate spinel (LiTi2O4) with water at room temperature gives Li-deficient Li0.33Ti2O4. Combined X-ray and neutron Rietveld analysis shows that 28% of the Ti cations are displaced to alternative octahedral sites, in keeping with a proposed model based on Ti-migration limited by Li-vacancy concentration.
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Affiliation(s)
- A Kitada
- Department of Materials Science and Engineering, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan
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Decaroli C, Arevalo-Lopez AM, Woodall CH, Rodriguez EE, Attfield JP, Parker SF, Stock C. (C4H12N2)[CoCl4]: tetrahedrally coordinated Co2+without the orbital degeneracy. Acta Crystallogr B Struct Sci Cryst Eng Mater 2015; 71:20-4. [DOI: 10.1107/s2052520614024809] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 11/12/2014] [Indexed: 11/11/2022]
Abstract
We report on the synthesis, crystal structure and magnetic properties of a previously unreported Co2+S = {3\over 2} compound, (C4H12N2)[CoCl4], based upon a tetrahedral crystalline environment. The S = {3\over 2} magnetic ground state of Co2+, measured with magnetization, implies an absence of spin-orbit coupling and orbital degeneracy. This contrasts with compounds based upon an octahedral and even known tetrahedral Co2+[Cottonet al.(1961).J. Am. Chem. Soc.83, 4690] systems where a sizable spin-orbit coupling is measured. The compound is characterized with single-crystal X-ray diffraction, magnetic susceptibility, IR and UV–vis spectroscopy. Magnetic susceptibility measurements find no magnetic ordering above 2 K. The results are also compared with the previously known monoclinic hydrated analogue.
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Hallas AM, Cheng JG, Arevalo-Lopez AM, Silverstein HJ, Su Y, Sarte PM, Zhou HD, Choi ES, Attfield JP, Luke GM, Wiebe CR. Incipient ferromagnetism in Tb2Ge2O7: application of chemical pressure to the enigmatic spin-liquid compound Tb2Ti2O7. Phys Rev Lett 2014; 113:267205. [PMID: 25615381 DOI: 10.1103/physrevlett.113.267205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 06/04/2023]
Abstract
After nearly 20 years of study, the origin of the spin-liquid state in Tb2Ti2O7 remains a challenge for experimentalists and theorists alike. To improve our understanding of the exotic magnetism in Tb2Ti2O7, we synthesize a chemical pressure analog: Tb2Ge2O7. Substitution of titanium by germanium results in a lattice contraction and enhanced exchange interactions. We characterize the magnetic ground state of Tb2Ge2O7 with specific heat, ac and dc magnetic susceptibility, and polarized neutron scattering measurements. Akin to Tb2Ti2O7, there is no long-range order in Tb2Ge2O7 down to 20 mK. The Weiss temperature of -19.2(1) K, which is more negative than that of Tb2Ti2O7, supports the picture of stronger antiferromagnetic exchange. Polarized neutron scattering of Tb2Ge2O7 reveals that liquidlike correlations dominate in this system at 3.5 K. However, below 1 K, the liquidlike correlations give way to intense short-range ferromagnetic correlations with a length scale similar to the Tb-Tb nearest neighbor distance. Despite stronger antiferromagnetic exchange, the ground state of Tb2Ge2O7 has ferromagnetic character, in stark contrast to the pressure-induced antiferromagnetic order observed in Tb2Ti2O7.
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Affiliation(s)
- A M Hallas
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - J G Cheng
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - A M Arevalo-Lopez
- Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
| | - H J Silverstein
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Y Su
- Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - P M Sarte
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
| | - J P Attfield
- Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
| | - G M Luke
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z7, Canada
| | - C R Wiebe
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada and Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada and Department of Chemistry, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
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