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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] [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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Lawrence GB, Wildman EJ, Stenning GBG, Ritter C, Fauth F, Mclaughlin AC. Electronic and Magnetic Properties of Cation Ordered Sr 2Mn 2.23Cr 0.77As 2O 2. Inorg Chem 2020; 59:7553-7560. [PMID: 32432871 DOI: 10.1021/acs.inorgchem.0c00447] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several different mechanisms of magnetoresistance (MR) have been observed in 1111 LnMnAsO1-xFx oxypnictides (Ln = lanthanide) as a result of magnetic coupling between the Mn and Ln. Such phases also exhibit interesting magnetic phase transitions upon cooling. Sr2Mn2CrAs2O2 has been synthesized to investigate if it is possible to observe MR and/or magnetic phase transitions as a result of magnetic coupling between the Mn and Cr. Sr2Mn2CrAs2O2 crystallizes in the tetragonal space group I4/mmm containing alternating MO22- and M'2As22- layers, and neutron diffraction results demonstrate that the actual stoichiometry is Sr2Mn2.23Cr0.77As2O2. Cation order is present between Mn and Cr, with Cr predominantly occupying the square planar MO22- site. Below 410 K, the magnetic moments of the Mn/Cr ions in the M'2As22- sublattice exhibit G-type antiferromagnetic order. The Mn/Cr moments within the MO22- layer order below 167 K with a K2NiF4-type antiferromagnetic structure that simultaneously induces a spin flip of the magnetic moments in the M'2As22- layers from a G-type to a C-type antiferromagnetic arrangement. The results demonstrate that the superexchange interactions are finely balanced in Sr2Mn2.23Cr0.77As2O2. Sr2Mn2.23Cr0.77As2O2 is semiconducting, and there is no evidence of MR.
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Affiliation(s)
- Gaynor B Lawrence
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.,Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Eve J Wildman
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
| | - Gavin B G Stenning
- ISIS, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K
| | - Clemens Ritter
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Francois Fauth
- CELLS-ALBA Synchrotron, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Abbie C Mclaughlin
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
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Zhang F, Li B, Ren Q, Mao H, Xia Y, Hu B, Liu Z, Wang Z, Shao Y, Feng Z, Tan S, Sun Y, Ren Z, Jing Q, Liu B, Luo H, Ma J, Mei Y, Wang C, Cao GH. ThMnPnN (Pn = P, As): Synthesis, Structure, and Chemical Pressure Effects. Inorg Chem 2020; 59:2937-2944. [PMID: 32064866 DOI: 10.1021/acs.inorgchem.9b03294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mn-based ZrCuSiAs-type pnictides ThMnPnN (Pn = P, As) containing PbO-type Th2N2 layers were synthesized. The crystal and magnetic structures are determined using X-ray and neutron powder diffraction. While neutron diffraction indicates a C-type antiferromagnetic state at 300 K, the temperature dependence of the magnetic susceptibility shows cusps at 36 and 52 K respectively for ThMnPN and ThMnAsN. The susceptibility cusps are ascribed to a spontaneous antiferromagnetic-to-antiferromagnetic transition for Mn2+ moments, which is observed for the first time in Mn-based ZrCuSiAs-type compounds. In addition, measurements of the resistivity and specific heat suggest an abnormal increase in the density of states at the Fermi energy. The result is discussed in terms of the internal chemical pressure effect.
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Affiliation(s)
- Fuxiang Zhang
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Baizhuo Li
- Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
| | - Qingyong Ren
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Huican Mao
- Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875, P. R. China.,Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Yuanhua Xia
- Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, P. R. China
| | - Bingfeng Hu
- Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, P. R. China
| | - Zichen Liu
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Zhicheng Wang
- Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
| | - Yeting Shao
- Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
| | - Zhifa Feng
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Shugang Tan
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Yuping Sun
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Zhi Ren
- Institute for Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310027, P. R. China
| | - Qiang Jing
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Bo Liu
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Jie Ma
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Yuxue Mei
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Cao Wang
- School of Physics & Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, P. R. China
| | - Guang-Han Cao
- Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
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Wildman EJ, McCombie KS, Stenning GBG, Mclaughlin AC. The suppression of CMR in Nd(Mn 1-xCo x)AsO 0.95F 0.05. Dalton Trans 2018; 47:14726-14733. [PMID: 30280742 DOI: 10.1039/c8dt03071e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The colossal magnetoresistance (CMR) observed in the oxypnictide NdMnAsO1-xFx has been further investigated. The magnetotransport is dominated by magnetopolarons. Magnetoresistance measurements of the series Nd(Mn1-xCox)AsO0.95F0.05 show that doping with cobalt on the manganese site pins the magnetopolarons and suppresses the CMR, which is completely destroyed by x = 0.047. The chemical doping results in non-stoichiometric samples, with both As and O vacancies. The relationship between the non-stoichiometry, magnetic order, electron doping and CMR is explored. The Nd antiferromagnetic transition and simultaneous reorientation of the Mn spins into the basal plane at 23 K (TSR) is not effected by Co doping. However, there is a significant decrease in TN(Mn) as the antiferromagnetic transition is suppressed from 360 K to 300 K as x increases from 0-0.047. The manganese moment at 10 K is also reduced from 3.86(2)μB to 3.21(2)μB over the same doping range. This reduction in the in-plane Mn moment decreases the electron-electron correlations below TSR and acts to further diminish the magnetoresistance.
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Affiliation(s)
- E J Wildman
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, Scotland, UK.
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Stock C, McCabe EE. The magnetic and electronic properties of oxyselenides-influence of transition metal ions and lanthanides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:453001. [PMID: 27608752 DOI: 10.1088/0953-8984/28/45/453001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Magnetic oxyselenides have been a topic of research for several decades, firstly in the context of photoconductivity and thermoelectricity owing to their intrinsic semiconducting properties and ability to tune the energy gap through metal ion substitution. More recently, interest in the oxyselenides has experienced a resurgence owing to the possible relation to strongly correlated phenomena given the fact that many oxyselenides share a similar structure to unconventional superconducting pnictides and chalcogenides. The two dimensional nature of many oxyselenide systems also draws an analogy to cuprate physics where a strong interplay between unconventional electronic phases and localised magnetism has been studied for several decades. It is therefore timely to review the physics of the oxyselenides in the context of the broader field of strongly correlated magnetism and electronic phenomena. Here we review the current status and progress in this area of research with the focus on the influence of lanthanides and transition metal ions on the intertwined magnetic and electronic properties of oxyselenides. The emphasis of the review is on the magnetic properties and comparisons are made with iron based pnictide and chalcogenide systems.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, UK
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Wildman EJ, Mclaughlin AC. A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05. Sci Rep 2016; 6:20705. [PMID: 26875693 PMCID: PMC4753427 DOI: 10.1038/srep20705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/11/2016] [Indexed: 11/22/2022] Open
Abstract
The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95%). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.
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Affiliation(s)
- E J Wildman
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, Scotland
| | - A C Mclaughlin
- The Chemistry Department, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, Scotland
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