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Yu Y, Iskakov S, Gull E, Held K, Krien F. Unambiguous Fluctuation Decomposition of the Self-Energy: Pseudogap Physics beyond Spin Fluctuations. PHYSICAL REVIEW LETTERS 2024; 132:216501. [PMID: 38856250 DOI: 10.1103/physrevlett.132.216501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/15/2024] [Indexed: 06/11/2024]
Abstract
Correlated electron systems may give rise to multiple effective interactions whose combined impact on quasiparticle properties can be difficult to disentangle. We introduce an unambiguous decomposition of the electronic self-energy which allows us to quantify the contributions of various effective interactions simultaneously. We use this tool to revisit the hole-doped Hubbard model within the dynamical cluster approximation, where commonly spin fluctuations are considered to be the origin of the pseudogap. While our fluctuation decomposition confirms that spin fluctuations indeed suppress antinodal electronic spectral weight, we show that they alone cannot capture the pseudogap self-energy quantitatively. Nonlocal multiboson Feynman diagrams yield substantial contributions and are needed for a quantitative description of the pseudogap.
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Affiliation(s)
- Yang Yu
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Sergei Iskakov
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Emanuel Gull
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Karsten Held
- Institute for Solid State Physics, TU Wien, 1040 Vienna, Austria
| | - Friedrich Krien
- Institute for Solid State Physics, TU Wien, 1040 Vienna, Austria
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Park J, Huh S, Choi YW, Kang D, Kim M, Kim D, Park S, Choi HJ, Kim C, Yi Y. Visualizing the Low-Energy Electronic Structure of Prototypical Hybrid Halide Perovskite through Clear Band Measurements. ACS NANO 2024; 18:7570-7579. [PMID: 38377437 DOI: 10.1021/acsnano.3c12587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Organic-inorganic hybrid perovskites (OIHPs) are a promising class of materials that rival conventional semiconductors in various optoelectronic applications. However, unraveling the precise nature of their low-energy electronic structures continues to pose a significant challenge, primarily due to the absence of clear band measurements. Here, we investigate the low-energy electronic structure of CH3NH3PbI3 (MAPI3) using angle-resolved photoelectron spectroscopy combined with ab initio density functional theory. We successfully visualize the electronic structure of MAPI3 near the bulk valence band maximum by using a laboratory photon source (He Iα, 21.2 eV) at low temperature and explore its fundamental properties. The observed valence band exhibits a highly isotropic and parabolic band characterized by small effective masses of 0.20-0.21 me, without notable spectral signatures associated with a large polaron or the Rashba effect, subjects that are intensely debated in the literature. Concurrently, our spin-resolved measurements directly disprove the giant Rashba scenario previously suggested in a similar perovskite compound by establishing an upper limit for the Rashba parameter (αR) of 0.28 eV Å. Our results unveil the unusually complex nature of the low-energy electronic structure of OIHPs, thereby advancing our fundamental understanding of this important class of materials.
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Affiliation(s)
- Jeehong Park
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Soonsang Huh
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Young Woo Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Donghee Kang
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Minsoo Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Donghan Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Soohyung Park
- Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Hyoung Joon Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Yeonjin Yi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
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'True' bosonic coupling strength in strongly correlated superconductors. Sci Rep 2013; 3:1930. [PMID: 23722675 PMCID: PMC3668320 DOI: 10.1038/srep01930] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022] Open
Abstract
Clarifying the coupling between electrons and bosonic excitations (phonons or magnetic fluctuations) that mediate the formation of Cooper pairs is pivotal to understand superconductivity. Such coupling effects are contained in the electron self-energy, which is experimentally accessible via angle-resolved photoemission spectroscopy (ARPES). However, in unconventional superconductors, identifying the nature of the electron-boson coupling remains elusive partly because of the significant band renormalization due to electron correlation. Until now, to quantify the electron-boson coupling, the self-energy is most often determined by assuming a phenomenological ‘bare’ band. Here, we demonstrate that the conventional procedure underestimates the electron-boson coupling depending on the electron-electron coupling, even if the self-energy appears to be self-consistent via the Kramers-Kronig relation. Our refined method explains well the electron-boson and electron-electron coupling strength in ruthenate superconductor Sr2RuO4, calling for a critical revision of the bosonic coupling strength from ARPES self-energy in strongly correlated electron systems.
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Liu G, Wang G, Zhu Y, Zhang H, Zhang G, Wang X, Zhou Y, Zhang W, Liu H, Zhao L, Meng J, Dong X, Chen C, Xu Z, Zhou XJ. Development of a vacuum ultraviolet laser-based angle-resolved photoemission system with a superhigh energy resolution better than 1 meV. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:023105. [PMID: 18315281 DOI: 10.1063/1.2835901] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The design and performance of the first vacuum ultraviolet (VUV) laser-based angle-resolved photoemission (ARPES) system are described. The VUV laser with a photon energy of 6.994 eV and bandwidth of 0.26 meV is achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2. The new VUV laser-based ARPES system exhibits superior performance, including superhigh energy resolution better than 1 meV, high momentum resolution, superhigh photon flux, and much enhanced bulk sensitivity, which are demonstrated from measurements on a typical Bi2Sr2CaCu2O8 high temperature superconductor. Issues and further development related to the VUV laser-based photoemission technique are discussed.
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Affiliation(s)
- Guodong Liu
- National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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Forster F, Hüfner S, Reinert F. Rare Gases on Noble-Metal Surfaces: An Angle-Resolved Photoemission Study with High Energy Resolution. J Phys Chem B 2004. [DOI: 10.1021/jp049215b] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F. Forster
- Universität des Saarlandes, FR 7.2 Experimentalphysik, D-66041 Saarbrücken, Germany
| | - S. Hüfner
- Universität des Saarlandes, FR 7.2 Experimentalphysik, D-66041 Saarbrücken, Germany
| | - F. Reinert
- Universität Würzburg, Experimentelle Physik II, D-97074 Würzburg, Germany
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