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Chudzinski P, Berben M, Xu X, Wakeham N, Bernáth B, Duffy C, Hinlopen RDH, Hsu YT, Wiedmann S, Tinnemans P, Jin R, Greenblatt M, Hussey NE. Emergent symmetry in a low-dimensional superconductor on the edge of Mottness. Science 2023; 382:792-796. [PMID: 37972183 DOI: 10.1126/science.abp8948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
Upon cooling, condensed-matter systems typically transition into states of lower symmetry. The converse-i.e., the emergence of higher symmetry at lower temperatures-is extremely rare. In this work, we show how an unusually isotropic magnetoresistance in the highly anisotropic, one-dimensional conductor Li0.9Mo6O17 and its temperature dependence can be interpreted as a renormalization group (RG) flow toward a so-called separatrix. This approach is equivalent to an emergent symmetry in the system. The existence of two distinct ground states, Mott insulator and superconductor, can then be traced back to two opposing RG trajectories. By establishing a direct link between quantum field theory and an experimentally measurable quantity, we uncover a path through which emergent symmetry might be identified in other candidate materials.
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Affiliation(s)
- P Chudzinski
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - M Berben
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - Xiaofeng Xu
- Key Laboratory of Quantum Precision Measurement of Zhejiang Province, Department of Applied Physics, Zhejiang University of Technology, Hangzhou, China
| | - N Wakeham
- Center for Space Sciences and Technology, University of Maryland Baltimore, Baltimore, MD, USA
| | - B Bernáth
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - C Duffy
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - R D H Hinlopen
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Yu-Te Hsu
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - S Wiedmann
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - P Tinnemans
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
| | - Rongying Jin
- Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC, USA
| | - M Greenblatt
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, Netherlands
- Institute for Molecules and Materials, Radboud University, Nijmegen, Netherlands
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK
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Koley A, Maiti SK, Pérez LM, Silva JHO, Laroze D. Possible Routes to Obtain Enhanced Magnetoresistance in a Driven Quantum Heterostructure with a Quasi-Periodic Spacer. MICROMACHINES 2021; 12:mi12091021. [PMID: 34577665 PMCID: PMC8466401 DOI: 10.3390/mi12091021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 11/16/2022]
Abstract
In this work, we perform a numerical study of magnetoresistance in a one-dimensional quantum heterostructure, where the change in electrical resistance is measured between parallel and antiparallel configurations of magnetic layers. This layered structure also incorporates a non-magnetic spacer, subjected to quasi-periodic potentials, which is centrally clamped between two ferromagnetic layers. The efficiency of the magnetoresistance is further tuned by injecting unpolarized light on top of the two sided magnetic layers. Modulating the characteristic properties of different layers, the value of magnetoresistance can be enhanced significantly. The site energies of the spacer is modified through the well-known Aubry-André and Harper (AAH) potential, and the hopping parameter of magnetic layers is renormalized due to light irradiation. We describe the Hamiltonian of the layered structure within a tight-binding (TB) framework and investigate the transport properties through this nanojunction following Green's function formalism. The Floquet-Bloch (FB) anstaz within the minimal coupling scheme is introduced to incorporate the effect of light irradiation in TB Hamiltonian. Several interesting features of magnetotransport properties are represented considering the interplay between cosine modulated site energies of the central region and the hopping integral of the magnetic regions that are subjected to light irradiation. Finally, the effect of temperature on magnetoresistance is also investigated to make the model more realistic and suitable for device designing. Our analysis is purely a numerical one, and it leads to some fundamental prescriptions of obtaining enhanced magnetoresistance in multilayered systems.
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Affiliation(s)
- Arpita Koley
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700 108, India;
| | - Santanu K. Maiti
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700 108, India;
- Correspondence:
| | - Laura M. Pérez
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile; (L.M.P.); (D.L.)
| | - Judith Helena Ojeda Silva
- Grupo de Física de Materiales, Universidad Pedagógica y Tecnológica de Colombia, Tunja 150003, Colombia;
- Laboratorio de Química Teórica y Computacional, Grupo de Investigación Química-Física Molecular y Modelamiento Computacional (QUIMOL), Facultad de Ciencias, Universidad Pedagógica y Tecnológica de Colombia, Tunja 150003, Colombia
| | - David Laroze
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile; (L.M.P.); (D.L.)
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Song Z, Li B, Xu C, Wu S, Qian B, Chen T, Biswas PK, Xu X, Sun J. Pressure engineering of the Dirac fermions in quasi-one-dimensional Tl 2Mo 6Se 6. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:215402. [PMID: 32032009 DOI: 10.1088/1361-648x/ab73a8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Topological band dispersions other than the standard Dirac or Weyl fermions have garnered the increasing interest in materials science. Among them, the cubic Dirac fermions were recently proposed in the family of quasi-one-dimensional (q-1D) conductors A2Mo6X6 (A = Na, K, In, Tl; X = S, Se, Te), where the band crossing is characterized by a linear dispersion in one k-space direction but the cubic dispersion in the plane perpendicular to it. It is not yet clear, however, how the external perturbations can alter these nontrivial carriers and ultimately induce a new distinct quantum phase. Here we study the evolution of Dirac fermions, in particular the cubic Dirac crossing, under external pressure in the representative q-1D Tl2Mo6Se6 via the first-principles calculations. Specifically, it is found that the topological properties, including the bulk Dirac crossings and the topological surface states, change progressively under pressure up to 50 GPa where it undergoes a structural transition from the hexagonal phase to body-centered tetragonal phase. Above 50 GPa, the system is more likely to be topologically trivial. Further, we also investigate its phonon spectra, which reveals a gradual depletion of the negative phonon modes with pressure, consistent with the more three-dimensional Fermi surface in the high-pressure phase. Our work may provide a useful guideline for further experimental search and the band engineering of the topologically nontrivial fermions in this intriguing state of matter.
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Affiliation(s)
- Ziwan Song
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, People's Republic of China
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