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Tresca C, Brun C, Bilgeri T, Menard G, Cherkez V, Federicci R, Longo D, Debontridder F, D'angelo M, Roditchev D, Profeta G, Calandra M, Cren T. Chiral Spin Texture in the Charge-Density-Wave Phase of the Correlated Metallic Pb/Si(111) Monolayer. PHYSICAL REVIEW LETTERS 2018; 120:196402. [PMID: 29799266 DOI: 10.1103/physrevlett.120.196402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 03/23/2018] [Indexed: 06/08/2023]
Abstract
We investigate the 1/3 monolayer α-Pb/Si(111) surface by scanning tunneling spectroscopy (STS) and fully relativistic first-principles calculations. We study both the high-temperature sqrt[3]×sqrt[3] and low-temperature 3×3 reconstructions and show that, in both phases, the spin-orbit interaction leads to an energy splitting as large as 25% of the valence-band bandwidth. Relativistic effects, electronic correlations, and Pb-substrate interaction cooperate to stabilize a correlated low-temperature paramagnetic phase with well-developed lower and upper Hubbard bands coexisting with 3×3 periodicity. By comparing the Fourier transform of STS conductance maps at the Fermi level with calculated quasiparticle interference from nonmagnetic impurities, we demonstrate the occurrence of two large hexagonal Fermi sheets with in-plane spin polarizations and opposite helicities.
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Affiliation(s)
- C Tresca
- Department of Physical and Chemical Sciences and SPIN-CNR, University of L'Aquila, Via Vetoio 10, I-67100 L'Aquila, Italy
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - C Brun
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - T Bilgeri
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - G Menard
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - V Cherkez
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - R Federicci
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - D Longo
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - F Debontridder
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - M D'angelo
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - D Roditchev
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
- Laboratoire de physique et d'étude des matériaux, LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, 10 rue Vauquelin, F-75005 Paris, France
| | - G Profeta
- Department of Physical and Chemical Sciences and SPIN-CNR, University of L'Aquila, Via Vetoio 10, I-67100 L'Aquila, Italy
| | - M Calandra
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - T Cren
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
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Martins C, Aichhorn M, Biermann S. Coulomb correlations in 4d and 5d oxides from first principles-or how spin-orbit materials choose their effective orbital degeneracies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:263001. [PMID: 28262638 DOI: 10.1088/1361-648x/aa648f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The interplay of spin-orbit coupling and Coulomb correlations has become a hot topic in condensed matter theory and is especially important in 4d and 5d transition metal oxides, like iridates or rhodates. Here, we review recent advances in dynamical mean-field theory (DMFT)-based electronic structure calculations for treating such compounds, introducing all necessary implementation details. We also discuss the evaluation of Hubbard interactions in spin-orbit materials. As an example, we perform DMFT calculations on insulating strontium iridate (Sr2IrO4) and its 4d metallic counterpart, strontium rhodate (Sr2RhO4). While a Mott-insulating state is obtained for Sr2IrO4 in its paramagnetic phase, the spectral properties and Fermi surfaces obtained for Sr2RhO4 show excellent agreement with available experimental data. Finally, we discuss the electronic structure of these two compounds by introducing the notion of effective spin-orbital degeneracy as the key quantity that determines the correlation strength. We stress that effective spin-orbital degeneracy introduces an additional axis into the conventional picture of a phase diagram based on filling and on the ratio of interactions to bandwidth, analogous to the degeneracy-controlled Mott transition in d1 perovskites.
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Affiliation(s)
- C Martins
- Laboratoire de Chimie et Physique Quantiques, UMR 5626, Université Paul Sabatier, 118 route de Narbonne, 31400 Toulouse, France
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Hansmann P, Ayral T, Tejeda A, Biermann S. Uncertainty principle for experimental measurements: Fast versus slow probes. Sci Rep 2016; 6:19728. [PMID: 26829902 PMCID: PMC4735290 DOI: 10.1038/srep19728] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 12/17/2015] [Indexed: 11/10/2022] Open
Abstract
The result of a physical measurement depends on the time scale of the experimental probe. In solid-state systems, this simple quantum mechanical principle has far-reaching consequences: the interplay of several degrees of freedom close to charge, spin or orbital instabilities combined with the disparity of the time scales associated to their fluctuations can lead to seemingly contradictory experimental findings. A particularly striking example is provided by systems of adatoms adsorbed on semiconductor surfaces where different experiments--angle-resolved photoemission, scanning tunneling microscopy and core-level spectroscopy--suggest different ordering phenomena. Using most recent first principles many-body techniques, we resolve this puzzle by invoking the time scales of fluctuations when approaching the different instabilities. These findings suggest a re-interpretation of ordering phenomena and their fluctuations in a wide class of solid-state systems ranging from organic materials to high-temperature superconducting cuprates.
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Affiliation(s)
- P Hansmann
- Centre de Physique Théorique, Ecole Polytechnique, CNRS, Univ. Paris-Saclay, 91128 Palaiseau, France.,Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - T Ayral
- Centre de Physique Théorique, Ecole Polytechnique, CNRS, Univ. Paris-Saclay, 91128 Palaiseau, France.,Institut de Physique Théorique (IPhT), CEA, CNRS, URA 2306, 91191 Gif-sur-Yvette, France
| | - A Tejeda
- Laboratoire de Physique des Solides, CNRS, Univ. Paris Sud, Univ. Paris-Saclay, 91405 Orsay, France
| | - S Biermann
- Centre de Physique Théorique, Ecole Polytechnique, CNRS, Univ. Paris-Saclay, 91128 Palaiseau, France.,Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France.,European Theoretical Synchrotron Facility, Europe
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Lantz G, Hajlaoui M, Papalazarou E, Jacques VLR, Mazzotti A, Marsi M, Lupi S, Amati M, Gregoratti L, Si L, Zhong Z, Held K. Surface Effects on the Mott-Hubbard Transition in Archetypal V{2}O{3}. PHYSICAL REVIEW LETTERS 2015; 115:236802. [PMID: 26684133 DOI: 10.1103/physrevlett.115.236802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Indexed: 06/05/2023]
Abstract
We present an experimental and theoretical study exploring surface effects on the evolution of the metal-insulator transition in the model Mott-Hubbard compound Cr-doped V{2}O{3}. We find a microscopic domain formation that is clearly affected by the surface crystallographic orientation. Using scanning photoelectron microscopy and x-ray diffraction, we find that surface defects act as nucleation centers for the formation of domains at the temperature-induced isostructural transition and favor the formation of microscopic metallic regions. A density-functional theory plus dynamical mean-field theory study of different surface terminations shows that the surface reconstruction with excess vanadyl cations leads to doped, and hence more metallic, surface states, which explains our experimental observations.
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Affiliation(s)
- G Lantz
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - M Hajlaoui
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - E Papalazarou
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - V L R Jacques
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - A Mazzotti
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - M Marsi
- Laboratoire de Physique des Solides, CNRS-UMR 8502, Université Paris-Sud, F-91405 Orsay, France
| | - S Lupi
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro, I-00185 Roma, Italy
| | - M Amati
- Elettra-Sincrotrone Trieste SCpA, SS 14 km 163.5 AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - L Gregoratti
- Elettra-Sincrotrone Trieste SCpA, SS 14 km 163.5 AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - L Si
- Institute for Solid State Physics, Vienna University of Technology, AT-1040 Vienna, Austria
| | - Z Zhong
- Institute for Solid State Physics, Vienna University of Technology, AT-1040 Vienna, Austria
- Institute for Theoretical and Astrophysics, University of Würzburg, Am Hubland, 9704 Würzburg, Germany
| | - K Held
- Institute for Solid State Physics, Vienna University of Technology, AT-1040 Vienna, Austria
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Biermann S. Dynamical screening effects in correlated electron materials-a progress report on combined many-body perturbation and dynamical mean field theory: 'GW + DMFT'. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:173202. [PMID: 24722486 DOI: 10.1088/0953-8984/26/17/173202] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We give a summary of recent progress in the field of electronic structure calculations for materials with strong electronic Coulomb correlations. The discussion focuses on developments beyond the by now well established combination of density functional and dynamical mean field theory dubbed 'LDA + DMFT'. It is organized around the description of dynamical screening effects in the solid. Indeed, screening in the solid gives rise to dynamical local Coulomb interactions U(ω) (Aryasetiawan et al 2004 Phys. Rev. B 70 195104), and this frequency dependence leads to effects that cannot be neglected in a truly first principles description. We review the recently introduced extension of LDA + DMFT to dynamical local Coulomb interactions 'LDA + U(ω) + DMFT' (Casula et al 2012 Phys. Rev. B 85 035115, Werner et al 2012 Nature Phys. 1745-2481). A reliable description of dynamical screening effects is also a central ingredient of the 'GW + DMFT' scheme (Biermann et al 2003 Phys. Rev. Lett. 90 086402), a combination of many-body perturbation theory in Hedin's GW approximation and dynamical mean field theory. Recently, the first GW + DMFT calculations including dynamical screening effects for real materials have been achieved, with applications to SrV O3 (Tomczak et al 2012 Europhys. Lett. 100 67001, Tomczak et al Phys. Rev. B submitted (available electronically as arXiv:1312.7546)) and adatom systems on surfaces (Hansmann et al 2013 Phys. Rev. Lett. 110 166401). We review these and comment on further perspectives in the field. This review is an attempt to put elements of the original works into the broad perspective of the development of truly first principles techniques for correlated electron materials.
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Affiliation(s)
- Silke Biermann
- Centre de Physique Théorique, CNRS UMR7644, Ecole Polytechnique, F-91128 Palaiseau, France
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Hansmann P, Ayral T, Vaugier L, Werner P, Biermann S. Long-range Coulomb interactions in surface systems: a first-principles description within self-consistently combined GW and dynamical mean-field theory. PHYSICAL REVIEW LETTERS 2013; 110:166401. [PMID: 23679625 DOI: 10.1103/physrevlett.110.166401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Indexed: 06/02/2023]
Abstract
Systems of adatoms on semiconductor surfaces display competing ground states and exotic spectral properties typical of two-dimensional correlated electron materials which are dominated by a complex interplay of spin and charge degrees of freedom. We report a fully ab initio derivation of low-energy Hamiltonians for the adatom systems Si(111):X, with X=Sn, Si, C, Pb, that we solve within self-consistently combined GW and dynamical mean-field theory. Calculated photoemission spectra are in agreement with available experimental data. We rationalize experimentally observed trends from Mott physics toward charge ordering along the series as resulting from substantial long-range interactions.
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Affiliation(s)
- P Hansmann
- Centre de Physique Théorique, Ecole Polytechnique, CNRS UMR7644, 91128 Palaiseau, France
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