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Ye Z, Fang Y, Zhang H, Zhang F, Wu S, Lu WC, Yao YX, Wang CZ, Ho KM. The Gutzwiller conjugate gradient minimization method for correlated electron systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:243001. [PMID: 35290968 DOI: 10.1088/1361-648x/ac5e03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
We review our recent work on the Gutzwiller conjugate gradient minimization method, anab initioapproach developed for correlated electron systems. The complete formalism has been outlined that allows for a systematic understanding of the method, followed by a discussion of benchmark studies of dimers, one- and two-dimensional single-band Hubbard models. In the end, we present some preliminary results of multi-band Hubbard models and large-basis calculations of F2to illustrate our efforts to further reduce the computational complexity.
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Affiliation(s)
- Zhuo Ye
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
| | - Yimei Fang
- Department of Physics, OSED, Key Laboratory of Low Dimensional Condensed Matter Physics, (Department of Education of Fujian Province) Jiujiang Research Institute, Xiamen University, Xiamen 361005, People's Republic of China
| | - Han Zhang
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - Feng Zhang
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
| | - Shunqing Wu
- Department of Physics, OSED, Key Laboratory of Low Dimensional Condensed Matter Physics, (Department of Education of Fujian Province) Jiujiang Research Institute, Xiamen University, Xiamen 361005, People's Republic of China
| | - Wen-Cai Lu
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - Yong-Xin Yao
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
| | - Cai-Zhuang Wang
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
| | - Kai-Ming Ho
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
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2
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He Z, Song Y, Zhou K, Guo S, Wu J, Yin C, Guo Z, He L, Huang Q, Li L, Huang R, Guo J, Xing X, Chen J. Correlation of Tunable CoSi 4 Tetrahedron with the Superconducting Properties of LaCoSi. Inorg Chem 2021; 60:10880-10884. [PMID: 34288645 PMCID: PMC11165618 DOI: 10.1021/acs.inorgchem.1c01369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is known that as the FeAs4 tetrahedron in the Fe-based superconductor is close to the regular tetrahedron, critical temperature (Tc) can be greatly increased. Recently, a Co-based superconductor of LaCoSi (4 K) with "111" structure was found. In this work, we improve the Tc of LaCoSi through structural regulation. Tc can be increased by the chemical substitution of Co by Fe, while the superconductivity is suppressed by the Ni substitution. The combined analysis of neutron and synchrotron X-ray powder diffractions reveals that the change of the Si-Co-Si bond angles of the CoSi4 tetrahedron is possibly responsible for the determination of superconducting properties. The Fe chemical substitution is favorable for the formation of the regular tetrahedron of CoSi4. The present new Co-based superconductor of LaCoSi provides a possible method to enhance the superconductivity performance of the Co-based superconductors via controlling Co-based tetrahedra similar to those well established in the Fe-based superconductors.
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Affiliation(s)
- Zhengwen He
- Beijing Advanced Innovation Center for Materials Genome Engineering and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Yuzhu Song
- Beijing Advanced Innovation Center for Materials Genome Engineering and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Kaiyao Zhou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Shibin Guo
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100049, China
| | - Junkun Wu
- MOE Key Laboratory of New Processing Technology for Nonferrous Metal and Materials, Guangxi Key Laboratory of Optic and Electronic Materials and Devices, College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, P. R. China
| | - Congling Yin
- MOE Key Laboratory of New Processing Technology for Nonferrous Metal and Materials, Guangxi Key Laboratory of Optic and Electronic Materials and Devices, College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, P. R. China
| | - Zhongnan Guo
- Department of Chemistry, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Lunhua He
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Qingzhen Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, United States
| | - Laifeng Li
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100049, China
| | - Rongjin Huang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100049, China
| | - Jiangang Guo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
| | - Xianran Xing
- Beijing Advanced Innovation Center for Materials Genome Engineering and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Jun Chen
- Beijing Advanced Innovation Center for Materials Genome Engineering and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
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3
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A benchmark of Gutzwiller conjugate gradient minimization method in ground state energy calculations of dimers. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Ye Z, Yao YX, Zhao X, Wang CZ, Ho KM. First-principles calculation of correlated electron materials based on Gutzwiller wave function beyond Gutzwiller approximation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:335601. [PMID: 31067512 DOI: 10.1088/1361-648x/ab2032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We propose an approach that is under the framework of Gutzwiller wave function but goes beyond the commonly adopted Gutzwiller approximation to improve the accuracy and flexibility in treating the correlation effects. Detailed formalism is described for a dimer which is straightforwardly generalized later to more complicated periodic bulk systems. The accuracy of the approach is demonstrated by evaluating the potential energy curves of spin-singlet N2 dimer, spin-triplet O2 dimer, and 1D hydrogen chain. The computational workload of the approach can be easily handled by efficient parallel computing.
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Affiliation(s)
- Zhuo Ye
- Ames Laboratory-US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States of America
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5
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Zhang H, Lu WC, Yao YX, Wang CZ, Ho KM. Benchmark of correlation matrix renormalization method in molecule calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:195902. [PMID: 30736027 DOI: 10.1088/1361-648x/ab05b3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report benchmark calculations of the correlation matrix renormalization (CMR) approach for 23 molecules in the well-established G2 molecule set. This subset represents molecules with spin-singlet ground state in a variety of chemical bonding and coordination environments. The QUAsi-atomic minimal basis-set orbitals (QUAMBOs) are used as local orbitals in both CMR and full configuration interaction (FCI) calculations for comparison. The results obtained from the calculations are also compared with available experimental data. It is shown that the CMR method produces binding and dissociation energy curves in good agreement with the QUAMBO-FCI calculations as well as experimental results. The CMR benchmark calculations yield a standard deviation of 0.09 Å for the equilibrium bond length and 0.018 Hartree/atom for the formation energy, with a gain of great computational efficiency which scales like Hartree-Fock method.
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Affiliation(s)
- Han Zhang
- College of Physics and State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, Shandong 266071, People's Republic of China
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6
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Liu C, Liu J, Yao Y, Wang C, Ho K. Sum-rule corrections: a route to error cancellations in correlation matrix renormalisation theory. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1278800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- C. Liu
- Ames Laboratory–US DOE , Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University , Ames, IA, USA
| | - J. Liu
- Ames Laboratory–US DOE , Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University , Ames, IA, USA
| | - Y.X. Yao
- Ames Laboratory–US DOE , Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University , Ames, IA, USA
| | - C.Z. Wang
- Ames Laboratory–US DOE , Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University , Ames, IA, USA
| | - K.M. Ho
- Ames Laboratory–US DOE , Ames, IA, USA
- Department of Physics and Astronomy, Iowa State University , Ames, IA, USA
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7
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Fabrizio M. Quantum fluctuations beyond the Gutzwiller approximation. PHYSICAL REVIEW. B 2017; 95:075156. [PMID: 28503672 PMCID: PMC5424883 DOI: 10.1103/physrevb.95.075156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a simple scheme to evaluate linear response functions including quantum fluctuation corrections on top of the Gutzwiller approximation. The method is derived for a generic multiband lattice Hamiltonian without any assumption about the dynamics of the variational correlation parameters that define the Gutzwiller wavefunction, and which thus behave as genuine dynamical degrees of freedom that add on those of the variational uncorrelated Slater determinant. We apply the method to the standard half-filled single-band Hubbard model. We are able to recover known results, but, as by-product, we also obtain few novel ones. In particular, we show that quantum fluctuations can reproduce almost quantitatively the behaviour of the uniform magnetic susceptibility uncovered by dynamical mean field theory, which, though enhanced by correlations, is found to be smooth across the paramagnetic Mott transition. By contrast, the simple Gutzwiller approximation predicts that susceptibility to diverge at the transition.
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Affiliation(s)
- Michele Fabrizio
- International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
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8
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Liu C, Liu J, Yao YX, Wu P, Wang CZ, Ho KM. Correlation Matrix Renormalization Theory: Improving Accuracy with Two-Electron Density-Matrix Sum Rules. J Chem Theory Comput 2016; 12:4806-4811. [DOI: 10.1021/acs.jctc.6b00570] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Liu
- Ames
Laboratory−US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - J. Liu
- Ames
Laboratory−US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - Y. X. Yao
- Ames
Laboratory−US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - P. Wu
- Hefei
National Laboratory for Physical Sciences at Microscale, International
Center for Quantum Design of Functional Materials (ICQD) and Synergetic
Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - C. Z. Wang
- Ames
Laboratory−US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - K. M. Ho
- Ames
Laboratory−US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
- Hefei
National Laboratory for Physical Sciences at Microscale, International
Center for Quantum Design of Functional Materials (ICQD) and Synergetic
Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Yao YX, Liu J, Liu C, Lu WC, Wang CZ, Ho KM. Efficient and accurate treatment of electron correlations with Correlation Matrix Renormalization theory. Sci Rep 2015; 5:13478. [PMID: 26315767 PMCID: PMC4551991 DOI: 10.1038/srep13478] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 07/14/2015] [Indexed: 11/09/2022] Open
Abstract
We present an efficient method for calculating the electronic structure and total energy of strongly correlated electron systems. The method extends the traditional Gutzwiller approximation for one-particle operators to the evaluation of the expectation values of two particle operators in the many-electron Hamiltonian. The method is free of adjustable Coulomb parameters, and has no double counting issues in the calculation of total energy, and has the correct atomic limit. We demonstrate that the method describes well the bonding and dissociation behaviors of the hydrogen and nitrogen clusters, as well as the ammonia composed of hydrogen and nitrogen atoms. We also show that the method can satisfactorily tackle great challenging problems faced by the density functional theory recently discussed in the literature. The computational workload of our method is similar to the Hartree-Fock approach while the results are comparable to high-level quantum chemistry calculations.
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Affiliation(s)
- Y. X. Yao
- Ames Laboratory–US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - J. Liu
- Ames Laboratory–US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - C. Liu
- Ames Laboratory–US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - W. C. Lu
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin 130021, China
- College of Physical Science and Laboratory of Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao University, Qingdao, Shandong 266071, China
| | - C. Z. Wang
- Ames Laboratory–US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - K. M. Ho
- Ames Laboratory–US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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10
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Oh H, Coh S, Cohen ML. Calculation of the specific heat of optimally K-doped BaFe₂As₂. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:335504. [PMID: 26241358 DOI: 10.1088/0953-8984/27/33/335504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The calculated specific heat of optimally K-doped BaFe2As2 in density functional theory is about five times smaller than that found in the experiment. We report that by adjusting the potential on the iron atom to be slightly more repulsive for electrons improves the calculated heat capacity as well as the electronic band structure of Ba0.6K0.4Fe2As2. In addition, structural and magnetic properties are moved in the direction of experimental values. Applying the same correction to the antiferromagnetic state, we find that the electron-phonon coupling is strongly enhanced.
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Affiliation(s)
- Hyungju Oh
- Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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11
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van Roekeghem A, Ayral T, Tomczak JM, Casula M, Xu N, Ding H, Ferrero M, Parcollet O, Jiang H, Biermann S. Dynamical correlations and screened exchange on the experimental bench: spectral properties of the cobalt pnictide BaCo2As2. PHYSICAL REVIEW LETTERS 2014; 113:266403. [PMID: 25615361 DOI: 10.1103/physrevlett.113.266403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Indexed: 06/04/2023]
Abstract
Understanding the Fermi surface and low-energy excitations of iron or cobalt pnictides is crucial for assessing electronic instabilities such as magnetic or superconducting states. Here, we propose and implement a new approach to compute the low-energy properties of correlated electron materials, taking into account both screened exchange beyond the local density approximation and local dynamical correlations. The scheme allows us to resolve the puzzle of BaCo2As2, for which standard electronic structure techniques predict a ferromagnetic instability not observed in nature.
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Affiliation(s)
- Ambroise van Roekeghem
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Centre de Physique Théorique, Ecole Polytechnique, CNRS UMR 7644, 91128 Palaiseau, France
| | - Thomas Ayral
- Centre de Physique Théorique, Ecole Polytechnique, CNRS UMR 7644, 91128 Palaiseau, France and Institut de Physique Théorique (IPhT), CEA, CNRS, URA 2306, 91191 Gif-sur-Yvette, France
| | - Jan M Tomczak
- Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria
| | - Michele Casula
- CNRS and Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Université Pierre et Marie Curie, case 115, 4 place Jussieu, FR-75252 Paris Cedex 05, France
| | - Nan Xu
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Hong Ding
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Michel Ferrero
- Centre de Physique Théorique, Ecole Polytechnique, CNRS UMR 7644, 91128 Palaiseau, France
| | - Olivier Parcollet
- Institut de Physique Théorique (IPhT), CEA, CNRS, URA 2306, 91191 Gif-sur-Yvette, France
| | - Hong Jiang
- College of Chemistry and Molecular Engineering, Peking University, 100871 Beijing, China
| | - Silke Biermann
- Centre de Physique Théorique, Ecole Polytechnique, CNRS UMR 7644, 91128 Palaiseau, France and Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
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12
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Ma JZ, van Roekeghem A, Richard P, Liu ZH, Miao H, Zeng LK, Xu N, Shi M, Cao C, He JB, Chen GF, Sun YL, Cao GH, Wang SC, Biermann S, Qian T, Ding H. Correlation-induced self-doping in the iron-pnictide superconductor Ba2Ti2Fe2As4O. PHYSICAL REVIEW LETTERS 2014; 113:266407. [PMID: 25615365 DOI: 10.1103/physrevlett.113.266407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Indexed: 06/04/2023]
Abstract
The electronic structure of the iron-based superconductor Ba2Ti2Fe2As4O (Tc(onset)=23.5 K) has been investigated by using angle-resolved photoemission spectroscopy and combined local density approximation and dynamical mean field theory calculations. The electronic states near the Fermi level are dominated by both the Fe 3d and Ti 3d orbitals, indicating that the spacer layers separating different FeAs layers are also metallic. By counting the enclosed volumes of the Fermi surface sheets, we observe a large self-doping effect; i.e., 0.25 electrons per unit cell are transferred from the FeAs layer to the Ti2As2O layer, leaving the FeAs layer in a hole-doped state. This exotic behavior is successfully reproduced by our dynamical mean field calculations, in which the self-doping effect is attributed to the electronic correlations in the 3d shells. Our work provides an alternative route of effective doping without element substitution for iron-based superconductors.
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Affiliation(s)
- J-Z Ma
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - A van Roekeghem
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France
| | - P Richard
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Z-H Liu
- Department of Physics, Renmin University, Beijing 100872, China
| | - H Miao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - L-K Zeng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - N Xu
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
| | - C Cao
- Department of Physics, Condensed Matter Physics Group, Hangzhou Normal University, Hangzhou 310036, China
| | - J-B He
- Department of Physics, Renmin University, Beijing 100872, China
| | - G-F Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Collaborative Innovation Center of Quantum Matter, Beijing, China and Department of Physics, Renmin University, Beijing 100872, China
| | - Y-L Sun
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - G-H Cao
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - S-C Wang
- Department of Physics, Renmin University, Beijing 100872, China
| | - S Biermann
- Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France and Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France and European Theoretical Synchrotron Facility (ETSF), Europe
| | - T Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Collaborative Innovation Center of Quantum Matter, Beijing, China
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13
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Tomczak JM, van Schilfgaarde M, Kotliar G. Many-body effects in iron pnictides and chalcogenides: nonlocal versus dynamic origin of effective masses. PHYSICAL REVIEW LETTERS 2012; 109:237010. [PMID: 23368252 DOI: 10.1103/physrevlett.109.237010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Indexed: 06/01/2023]
Abstract
We apply the quasiparticle self-consistent GW approximation (QSGW) to some of the iron pnictide and chalcogenide superconductors. We compute Fermi surfaces and density of states, and find excellent agreement with experiment, substantially improving over standard band-structure methods. Analyzing the QSGW self-energy we discuss nonlocal and dynamic contributions to effective masses. We present evidence that the two contributions are mostly separable, since the quasiparticle weight is found to be essentially independent of momentum. The main effect of nonlocality is captured by the static but nonlocal QSGW effective potential. Moreover, these nonlocal self-energy corrections, absent in, e.g., dynamical mean field theory, can be relatively large. We show, on the other hand, that QSGW only partially accounts for dynamic renormalizations at low energies. These findings suggest that QSGW combined with dynamical mean field theory will capture most of the many-body physics in the iron pnictides and chalcogenides.
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Affiliation(s)
- Jan M Tomczak
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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14
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Wang NL, Hu WZ, Chen ZG, Yuan RH, Li G, Chen GF, Xiang T. High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:294202. [PMID: 22773312 DOI: 10.1088/0953-8984/24/29/294202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report optical spectroscopic measurements on electron- and hole-doped BaFe2As2. We show that the compounds in the normal state are not simple metals. The optical conductivity spectra contain, in addition to the free carrier response at low frequency, a temperature-dependent gap-like suppression at fairly high energy scale near 0.6 eV. This suppression evolves with the As–Fe–As bond angle induced by electron or hole doping. Furthermore, the feature becomes much weaker in the Fe-chalcogenide compounds. We elaborate that the feature is mainly caused by the strong Hund's rule coupling effect between the itinerant electrons and localized electron moment arising from the multiple Fe 3d orbitals. The coupling strength changes with the environment of the Fe atom. Our experiments demonstrate the coexistence of itinerant and localized electrons in iron-based compounds, which would then lead to a more comprehensive picture of the metallic magnetism in the materials.
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Affiliation(s)
- N L Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy ofSciences, Beijing 100190, People’s Republic of China
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15
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Oelsen EV, Seibold G, Bünemann J. Time-dependent Gutzwiller theory for multiband Hubbard models. PHYSICAL REVIEW LETTERS 2011; 107:076402. [PMID: 21902408 DOI: 10.1103/physrevlett.107.076402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Indexed: 05/31/2023]
Abstract
Based on the variational Gutzwiller theory, we present a method for the computation of response functions for multiband Hubbard models with general local Coulomb interactions. The improvement over the conventional random-phase approximation is exemplified for an infinite-dimensional two-band Hubbard model where the incorporation of the local multiplet structure leads to a much larger sensitivity of ferromagnetism on the Hund coupling. Our method can be implemented into local-density approximation and Gutzwiller schemes and will therefore be an important tool for the computation of response functions for strongly correlated materials.
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Affiliation(s)
- E v Oelsen
- Institut für Physik, BTU Cottbus, Germany
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16
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Moon SJ, Homes CC, Akrap A, Xu ZJ, Wen JS, Lin ZW, Li Q, Gu GD, Basov DN. Incoherent c-axis interplane response of the iron chalcogenide FeTe(0.55)Se(0.45) superconductor from infrared spectroscopy. PHYSICAL REVIEW LETTERS 2011; 106:217001. [PMID: 21699329 DOI: 10.1103/physrevlett.106.217001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Indexed: 05/31/2023]
Abstract
We report on the interplane c-axis electronic response of FeTe(0.55)Se(0.45) investigated by infrared spectroscopy. We find that the normal-state c-axis electronic response of FeTe(0.55)Se(0.45) is incoherent and bears significant similarities to those of mildly underdoped cuprates. The c-axis optical conductivity σ(c)(ω) of FeTe(0.55)Se(0.45) does not display well-defined Drude response at all temperatures. As temperature decreases, σ(c)(ω) is continuously suppressed. The incoherent c-axis response is found to be related to the strong dissipation in the ab-plane transport: a pattern that holds true for various correlated materials as well as FeTe(0.55)Se(0.45).
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Affiliation(s)
- S J Moon
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
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Schickling T, Gebhard F, Bünemann J. Antiferromagnetic order in multiband Hubbard models for iron pnictides. PHYSICAL REVIEW LETTERS 2011; 106:146402. [PMID: 21561206 DOI: 10.1103/physrevlett.106.146402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Indexed: 05/30/2023]
Abstract
We investigate multiband Hubbard models for the three iron 3d t(2g) bands and the two iron 3d e(g) bands in LaOFeAs by means of the Gutzwiller variational theory. Our analysis of the paramagnetic ground state shows that neither Hartree-Fock mean-field theories nor effective spin models describe these systems adequately. In contrast to Hartree-Fock-type approaches, the Gutzwiller theory predicts that antiferromagnetic order requires substantial values of the local Hund's-rule exchange interaction. For the three-band model, the antiferromagnetic moment fits experimental data for a broad range of interaction parameters. However, for the more appropriate five-band model, the iron e(g) electrons polarize the t(2g) electrons and they substantially contribute to the ordered moment.
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Affiliation(s)
- T Schickling
- Fachbereich Physik, Philipps Universität, Renthof 6, 35032 Marburg, Germany
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Chen ZG, Dong T, Ruan RH, Hu BF, Cheng B, Hu WZ, Zheng P, Fang Z, Dai X, Wang NL. Measurement of the c-axis optical reflectance of AFe2As2 (A=Ba, Sr) single crystals: evidence of different mechanisms for the formation of two energy gaps. PHYSICAL REVIEW LETTERS 2010; 105:097003. [PMID: 20868186 DOI: 10.1103/physrevlett.105.097003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 06/21/2010] [Indexed: 05/29/2023]
Abstract
We present the c-axis optical reflectance measurement on single crystals of BaFe2As2 and SrFe2As2, the parent compounds of FeAs based superconductors. Different from the ab-plane optical response where two distinct energy gaps were observed in the spin-density-wave (SDW) state, only the smaller energy gap could be seen clearly for E∥c axis. The very pronounced energy gap structure seen at a higher energy scale for E∥ab plane is almost invisible. We propose a novel picture for the band structure evolution across the SDW transition and suggest different driving mechanisms for the formation of the two energy gaps.
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Affiliation(s)
- Z G Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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Zhou S, Wang Z. Electron correlation and spin density wave order in iron pnictides. PHYSICAL REVIEW LETTERS 2010; 105:096401. [PMID: 20868178 DOI: 10.1103/physrevlett.105.096401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2009] [Indexed: 05/29/2023]
Abstract
We study the correlation effects on the electronic structure, orbital and spin density wave (SDW) order in Fe pnictides. Using the multiorbital Hubbard model and Gutzwiller projection, we show that correlation effects are essential to stabilize the metallic SDW phase for the intermediate correlation strengths appropriate for pnictides. We find that the ordered moments depend sensitively on Hund's rule coupling J but weakly on the intraorbital Coulomb repulsion U, varying from 0.3μB to 1.5μB in the range J=0.3-0.8 eV for U=3-4 eV. We study the phase diagram, the evolution of the Fermi surface with the ordered moment, the effects of electron doping, and compare to recent experiments.
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Affiliation(s)
- Sen Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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