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Huang YN, Yu XL, Liu DY, Han MM. Role of Doping Effect and Chemical Pressure Effect Introduced by Alkali Metal Substitution on 1144 Iron-Based Superconductors. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16093343. [PMID: 37176225 PMCID: PMC10179702 DOI: 10.3390/ma16093343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 04/14/2023] [Accepted: 04/22/2023] [Indexed: 05/15/2023]
Abstract
CaAFe4As4 with A = K, Rb, and Cs are close to the doped 122 system, and the parent material can reach a superconducting transition temperature of 31-36 K without doping. To study the role of alkali metals, we investigated the induced hole doping and chemical pressure effects as a result of the introduction of alkali metals using density-functional-based methods. These two effects can affect the superconducting transition temperature by changing the number of electrons and the structure of the FeAs conductive layer, respectively. Our study shows that the dxz and dyz orbitals, which are degenerate in CaFe2As2, become nondegenerate in CaAFe4As4 due to two nonequivalent arsenic atoms (As1 and As2). The unusual oblate ellipsoid hole pocket at Γ point in CaAFe4As4 results from a divalent cation Ca2+ replaced by a monovalent cation A+. It shows one of the main differences in fermiology compared to a particular form of CaFe2As2 with reduced 1144 symmetry, due to the enhancement of As2-Fe hybridization. The unusual band appears in CaFe2As2 (1144) and gradually disappears in the change of K to Cs. Further analysis shows that this band is contributed by As1 and has strong dispersion perpendicular to the FeAs layer, suggesting that it is related to the peculiar van Hove singularity below the Fermi level. In addition, various aspects of CaFe2As2 (1144) and CaAFe4As4 in the ground state are discussed in terms of the influence of hole doping and chemical pressure.
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Affiliation(s)
- Yi-Na Huang
- Department of Physics, School of Science, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Da-Yong Liu
- Department of Physics, School of Sciences, Nantong University, Nantong 226019, China
| | - Miao-Miao Han
- School of Science, Huzhou University, Huzhou 313000, China
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Lee K, Hyun Jo N, Wang LL, Ribeiro RA, Kushnirenko Y, Schrunk B, Canfield PC, Kaminski A. Electronic signatures of successive itinerant, antiferromagnetic transitions in hexagonal La 2Ni 7. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:245501. [PMID: 36944256 DOI: 10.1088/1361-648x/acc629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/21/2023] [Indexed: 06/18/2023]
Abstract
We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations to study the electronic and magnetic properties of La2Ni7, an itinerant magnetic system with a series of three magnetic transition temperatures upon cooling, which end in a weak antiferromagnetic ground state. Our APRES data reveal several electron and hole pockets that have hexagonal symmetry near the Γ point. We observe significant reconstruction of the band structure upon successive magnetic transitions atT1∼ 61 K,T2∼ 57 K andT3∼ 42 K. Several features observed in ARPES data were reasonably well reproduced by DFT calculations, while others were not. In particular, the flat band nearEFpredicted by DFT in antiferromagnet (AFM) state, was seemingly absent in ARPES data. Our results detail the effects of magnetic ordering on the electronic structure in a Ni-based weak AFM and highlight challenges of current computational methods.
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Affiliation(s)
- Kyungchan Lee
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Na Hyun Jo
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Lin-Lin Wang
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - R A Ribeiro
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Yevhen Kushnirenko
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Ben Schrunk
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Paul C Canfield
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
| | - Adam Kaminski
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50014, United States of America
- Ames Laboratory US Department of Energy, Ames, IA 50011, United States of America
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Liu YB, Liu Y, Cao GH. Iron-based magnetic superconductors AEuFe 4As 4( A=Rb, Cs): natural superconductor-ferromagnet hybrids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:093001. [PMID: 34818630 DOI: 10.1088/1361-648x/ac3cf2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/24/2021] [Indexed: 06/13/2023]
Abstract
Superconductivity (SC) and ferromagnetism (FM) are normally antagonistic, and their coexistence in a single crystalline material appears to be very rare. Over a decade ago, the iron-based pnictides of doped EuFe2As2were found to render such a coexistence, primarily because of the Fe-3dmulti-orbitals which simultaneously satisfy the superconducting pairing and the ferromagnetic exchange interaction among Eu local spins. In 2016, the discovery of the iron-based superconductorsAEuFe4As4(A= Rb, Cs) provided an additional and complementary material basis for the study of the coexistence and the interplay between SC and FM. The two sibling compounds, which can be viewed as an intergrowth or a hybrid betweenAFe2As2and EuFe2As2, show SC in the FeAs bilayers atTc= 35-37 K and magnetic ordering atTm∼ 15 K in the sandwiched Eu2+-ion sheets. BelowTm, the Eu2+spins align ferromagnetically within each Eu plane, making the system as a natural atomic-thick superconductor-ferromagnet superlattice. This paper reviews the main research progress in the emerging topic during the past five years. An outlook for the future research opportunities is also presented.
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Affiliation(s)
- Ya-Bin Liu
- Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yi Liu
- Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310 023, People's Republic of China
| | - Guang-Han Cao
- Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Devices, Interdisciplinary Center for Quantum Information, and State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027, People's Republic of China
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Seidel S, Pöttgen R. Coloring and distortion variants of the bcc packing and for the aristotypes BaAl 4 and CeMg 2Si 2. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2021. [DOI: 10.1515/znb-2021-0022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The huge number of intermetallic structure types with many representatives calls for structural systemization. The combination of crystal chemistry with group theory is an efficient tool for such systemization and can be displayed in a concise and compact way via group-subgroup schemes. The present overview deals with such group-subgroup schemes (Bärnighausen trees) for coloring and distortion variants of the bcc packing as well as superstructures that derive from the aristotypes BaAl4 and CeMg2Si2.
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Affiliation(s)
- Stefan Seidel
- Institut für Anorganische und Analytische Chemie, Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
| | - Rainer Pöttgen
- Institut für Anorganische und Analytische Chemie, Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
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Lazarević N, Hackl R. Fluctuations and pairing in Fe-based superconductors: light scattering experiments. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:413001. [PMID: 32272462 DOI: 10.1088/1361-648x/ab8849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Inelastic scattering of visible light (Raman effect) offers a window into properties of correlated metals such as spin, electron and lattice dynamics as well as their mutual interactions. In this review we focus on electronic and spin excitations in Fe-based pnictides and chalcogenides, in particular but not exclusively superconductors. After a general introduction to the basic theory including the selection rules for the various scattering processes we provide an overview over the major experimental results. In the superconducting state below the transition temperatureTcthe pair-breaking effect can be observed, and the gap energies may be derived and associated with the gaps on the electron and hole bands. In spite of the similarities of the overall band structures the results are strongly dependent on the family and may even change qualitatively within one family. In some of the compounds strong collective modes appear belowTc. In Ba1-xKxFe2As2, which has the most isotropic gap of all Fe-based superconductors, there are indications that these modes are exciton-like states appearing in the presence of a hierarchy of pairing tendencies. The strong in-gap modes observed in Co-doped NaFeAs are interpreted in terms of quadrupolar orbital excitations which become undamped in the superconducting state. The doping dependence of the scattering intensity in Ba(Fe1-xCox)2As2is associated with a nematic resonance above a quantum critical point and interpreted in terms of a critical enhancement at the maximalTc. In the normal state the response from particle-hole excitations reflects the resistivity. In addition, there are strongly temperature-dependent contributions from presumably critical fluctuations in the energy range ofkBTwhich can be compared to the elastic properties. Currently it is not settled whether the fluctuations observed by light scattering are related to spin or charge. Another controversy relates to putative two-magnon excitations, typically in the energy range below 0.5 eV. Whereas this response presumably originates from charge excitations in most of the Fe-based compounds theory and experiment suggest that the excitations in the 60 meV range in FeSe stem from localized spins in a nearly frustrated system.
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Affiliation(s)
- N Lazarević
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - R Hackl
- Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
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Lee TH, Chubukov A, Miao H, Kotliar G. Pairing Mechanism in Hund's Metal Superconductors and the Universality of the Superconducting Gap to Critical Temperature Ratio. PHYSICAL REVIEW LETTERS 2018; 121:187003. [PMID: 30444397 DOI: 10.1103/physrevlett.121.187003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/20/2018] [Indexed: 06/09/2023]
Abstract
We analyze a simple model containing the physical ingredients of a Hund's metal, the local spin fluctuations with power-law correlators, (Ω_{0}/|Ω|)^{γ}, with γ greater than one, interacting with electronic quasiparticles. While the critical temperature and the gap change significantly with varying parameters, the 2Δ_{max}/k_{B}T_{c} remains close to twice the BCS value in agreement with experimental observations in the iron-based superconductors (FeSC).
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Affiliation(s)
- Tsung-Han Lee
- Physics and Astronomy Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Andrey Chubukov
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Hu Miao
- Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Gabriel Kotliar
- Physics and Astronomy Department, Rutgers University, Piscataway, New Jersey 08854, USA
- Brookhaven National Laboratory, Upton, New York 11973, USA
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Ding QP, Meier WR, Cui J, Xu M, Böhmer AE, Bud'ko SL, Canfield PC, Furukawa Y. Hedgehog Spin-Vortex Crystal Antiferromagnetic Quantum Criticality in CaK(Fe_{1-x}Ni_{x})_{4}As_{4} Revealed by NMR. PHYSICAL REVIEW LETTERS 2018; 121:137204. [PMID: 30312082 DOI: 10.1103/physrevlett.121.137204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Indexed: 06/08/2023]
Abstract
Two ordering states, antiferromagnetism and nematicity, have been observed in most iron-based superconductors (SCs). In contrast to those SCs, the newly discovered SC CaK(Fe_{1-x}Ni_{x})_{4}As_{4} exhibits an antiferromagnetic (AFM) state, called hedgehog spin-vortex crystal (SVC) structure, without nematic order, providing the opportunity for the investigation into the relationship between spin fluctuations and SC without any effects of nematic fluctuations. Our ^{75}As nuclear magnetic resonance studies on CaK(Fe_{1-x}Ni_{x})_{4}As_{4} (0≤x≤0.049) revealed that CaKFe_{4}As_{4} is located close to a hidden hedgehog SVC AFM quantum-critical point (QCP). The magnetic QCP without nematicity in CaK(Fe_{1-x}Ni_{x})_{4}As_{4} highlights the close connection of spin fluctuations and superconductivity in iron-based SCs. The advantage of stoichiometric composition also makes CaKFe_{4}As_{4} an ideal platform for further detailed investigation of the relationship between magnetic QCP and superconductivity in iron-based SCs without disorder effects.
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Affiliation(s)
- Q-P Ding
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - W R Meier
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - J Cui
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - M Xu
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - A E Böhmer
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - S L Bud'ko
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - P C Canfield
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Y Furukawa
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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Xie T, Wei Y, Gong D, Fennell T, Stuhr U, Kajimoto R, Ikeuchi K, Li S, Hu J, Luo H. Odd and Even Modes of Neutron Spin Resonance in the Bilayer Iron-Based Superconductor CaKFe_{4}As_{4}. PHYSICAL REVIEW LETTERS 2018; 120:267003. [PMID: 30004765 DOI: 10.1103/physrevlett.120.267003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Indexed: 06/08/2023]
Abstract
We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe_{4}As_{4}. In contrast to its quasi-two-dimensional electron structure, three strongly L-dependent modes of spin resonance are found below T_{c}=35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high-T_{c} superconducting families share a common nature.
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Affiliation(s)
- Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongliang Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Uwe Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Ryoichi Kajimoto
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Kazuhiko Ikeuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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