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Silkin VM, Chulkov EV, Echenique PM. Collective electronic excitations on the MgB2(0001) surfaces. ADVANCES IN QUANTUM CHEMISTRY 2019. [DOI: 10.1016/bs.aiq.2019.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Baldini E, Mann A, Benfatto L, Cappelluti E, Acocella A, Silkin VM, Eremeev SV, Kuzmenko AB, Borroni S, Tan T, Xi XX, Zerbetto F, Merlin R, Carbone F. Real-Time Observation of Phonon-Mediated σ-π Interband Scattering in MgB_{2}. PHYSICAL REVIEW LETTERS 2017; 119:097002. [PMID: 28949564 DOI: 10.1103/physrevlett.119.097002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Indexed: 06/07/2023]
Abstract
In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of E_{2g} phonons in the multiband superconductor MgB_{2} can be selectively enhanced by femtosecond laser pulses, leading to a transient control of the number of carriers in the σ-electronic subsystem. The nonequilibrium evolution of the material optical constants is followed in the spectral region sensitive to both the a- and c-axis plasma frequencies and modeled theoretically, revealing the details of the σ-π interband scattering mechanism in MgB_{2}.
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Affiliation(s)
- E Baldini
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - A Mann
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - L Benfatto
- Institute for Complex Systems-CNR, and Physics Department, University of Rome "La Sapienza", I-00185 Rome, Italy
| | - E Cappelluti
- Institute for Complex Systems-CNR, and Physics Department, University of Rome "La Sapienza", I-00185 Rome, Italy
| | - A Acocella
- Department of Chemistry "G. Ciamician," Università di Bologna, I-40126 Bologna, Italy
| | - V M Silkin
- Departamento de Física de Materiales, Universidad del País Vasco, 20080 San Sebastián/Donostia, Spain
- Donostia International Physics Center, 20018 San Sebastián/Donostia, Spain
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
| | - S V Eremeev
- Institute of Strength Physics and Materials Science, 634055 Tomsk, Russia
- Tomsk State University, 634050 , Tomsk, Russia
| | - A B Kuzmenko
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - S Borroni
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - T Tan
- Department of Material Science and Engineering, The Pennsylvania State University, Pennsylvania 16802, USA
| | - X X Xi
- Department of Material Science and Engineering, The Pennsylvania State University, Pennsylvania 16802, USA
| | - F Zerbetto
- Department of Chemistry "G. Ciamician," Università di Bologna, I-40126 Bologna, Italy
| | - R Merlin
- Department of Physics, Center for Photonics and Multiscale Nanomaterials, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - F Carbone
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Silkin VM, Nazarov VU, Chernov IP, Sklyadneva IY, Chulkov EV. Low-energy dielectric screening in Pd and PdHx systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:055501. [PMID: 25604038 DOI: 10.1088/0953-8984/27/5/055501] [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
Modifications in dielectric properties of palladium upon absorption of hydrogen are investigated theoretically in the low-energy (0-2 eV) region. The calculations were performed with full inclusion of the electronic band structure obtained within a self-consistent pseudopotential approach. In particular, we trace the evolution of the acoustic-like plasmon (AP) found previously in clean Pd with increasing hydrogen concentration. It exists in PdHx up to the hydrogen content x corresponding to the complete filling of the 4d Pd-derived energy bands because of the presence of two kinds of carriers at the Fermi surface. At higher H concentration the AP disappears since only one kind of carrier within the sp-like energy band exists at the Fermi level. Additionally, we investigate the spatial distribution inside the crystal of a potential caused by a time-dependent external perturbation and observe drastic modifications in the screening properties in the PdHx systems with energy and with hydrogen concentration.
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Affiliation(s)
- V M Silkin
- Departamento de Física de Materiales and Centro Mixto CSIC-UPV/EHU, Facultad de Ciencias Químicas, Universidad del País Vasco, Apdo. 1072, 20080 San Sebastián, Basque Country, Spain. Donostia International Physics Center (DIPC), P. de Manuel Lardizabal, 4, 20018 San Sebastián, Basque Country, Spain. IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain
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Hambach R, Giorgetti C, Hiraoka N, Cai YQ, Sottile F, Marinopoulos AG, Bechstedt F, Reining L. Anomalous angular dependence of the dynamic structure factor near Bragg reflections: graphite. PHYSICAL REVIEW LETTERS 2008; 101:266406. [PMID: 19437659 DOI: 10.1103/physrevlett.101.266406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The electron energy-loss function of graphite is studied for momentum transfers q beyond the first Brillouin zone. We find that near Bragg reflections the spectra can change drastically for very small variations in q. The effect is investigated by means of first principle calculations in the random phase approximation and confirmed by inelastic x-ray scattering measurements of the dynamic structure factor S(q, omega). We demonstrate that this effect is governed by crystal local field effects and the stacking of graphite. It is traced back to a strong coupling between excitations at small and large momentum transfers.
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Affiliation(s)
- R Hambach
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CEA/DSM, CNRS, 91128 Palaiseau, France
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