The Phonon Modes with Strong Electron–Phonon Interactions in p- and n-Type High T c Superconductors

2005 ◽  
Vol 18 (5-6) ◽  
pp. 779-783 ◽  
Author(s):  
S. Sugai ◽  
Y. Takayanagi ◽  
H. Suzuki ◽  
N. Hayamizu ◽  
Y. Sone ◽  
...  
Keyword(s):  
Phonon Modes ◽  
Strong Electron

scholarly journals The effect of strong electron-rattling phonon coupling on some superconducting properties

2019 ◽  
Vol 97 (5) ◽  
pp. 472-476
Author(s):  
Samin Tajik ◽  
Božidar Mitrović ◽  
Frank Marsiglio
Keyword(s):  
Temperature Dependence ◽  
Coupling Parameter ◽  
Nmr Relaxation ◽  
Superconducting Gap ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Strong Electron ◽  
Particle Decay ◽  
Electron Phonon Coupling ◽  
The One

Using the Eliashberg theory of superconductivity we have examined several properties of a model in which electrons are coupled only to rattling phonon modes represented by a sharp peak in the electron–phonon coupling function. Our choice of parameters was guided by experiments on β-pyrochlore oxide superconductor KOs2Os6. We have calculated the temperature dependence of the superconducting gap edge; the quasi-particle decay rate; the NMR relaxation rate assuming that the coupling between the nuclear spins and the conduction electrons is via a contact hyperfine interaction, which would be appropriate for the O-site in KOs2Os6; and the microwave conductivity. We examined the limit of very strong coupling by considering three values of the electron–phonon coupling parameter λ = 2.38, 3, and 5 and did not assume that the rattler frequency Ω0 is temperature dependent in the superconducting state. We obtained a very unusual temperature dependence of the superconducting gap edge Δ(T), very much like the one extracted from photoemission experiments on KOs2O6.

scholarly journals Single Molecule Fluorescence Spectroscopy of PSI Trimers from Arthrospira platensis: A Computational Approach

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 822 ◽  
Author(s):  
Roman Pishchalnikov ◽  
Vladimir Shubin ◽  
Andrei Razjivin
Keyword(s):  
Single Molecule ◽  
Fluorescence Spectra ◽  
Arthrospira Platensis ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Spectroscopy Analysis ◽  
Strong Electron ◽  
Zero Phonon Line ◽  
Electron Phonon Coupling ◽  
Single Molecule Fluorescence Spectroscopy

Based on single molecule spectroscopy analysis and our preliminary theoretical studies, the linear and fluorescence spectra of the PSI trimer from Arthrospira platensis with different realizations of the static disorder were modeled at cryogenic temperature. Considering the previously calculated spectral density of chlorophyll, an exciton model for the PSI monomer and trimer including the red antenna states was developed taking into account the supposed similarity of PSI antenna structures from Thermosynechococcus e., Synechocystis sp. PCC6803, and Arthrospira platensis. The red Chls in the PSI monomer were assumed to be in the nearest proximity of the reaction center. The PSI trimer model allowed the simulation of experimentally measured zero phonon line distribution of the red states considering a weak electron-phonon coupling for the antenna exciton states. However, the broad absorption and fluorescence spectra of an individual emitter at 760 nm were calculated by adjusting the Huang-Rhys factors of the chlorophyll lower phonon modes assuming strong electron-phonon coupling.

scholarly journals Low Energy Electrodynamics of CrI3 Layered Ferromagnet

2021 ◽  
Author(s):  
Luca Tomarchio ◽  
Salvatore Macis ◽  
Lorenzo Mosesso ◽  
Loi T. Nguyen ◽  
Antonio Grilli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Degrees Of Freedom ◽  
Near Infrared ◽  
Effective Interaction ◽  
Blue Shift ◽  
Ferromagnetic Phase ◽  
Phonon Modes ◽  
Strong Electron ◽  
Spin Lattice ◽  
Electron Phonon Interaction

Abstract We report on the optical properties from terahertz (THz) to Near-Infrared (NIR) of the layered magnetic compound CrI3 at various temperatures, both in the para- magnetic and ferromagnetic phase. In the NIR spectral range, we have observed an insulating electronic gap around 1.1 eV which strongly hardens with decreasing temperature. The blue shift observed represents a record in insulating materials and it is a fingerprint of a strong electron-phonon interaction. Moreover, a further gap hardening is observed below the Curie temperature, indicating the establishment of an effective interaction between electrons and magnetic degrees of freedom in the ferromagnetic phase. This interaction is confirmed by the disappearance of some phonon modes in the same phase as expected from a spin-lattice interaction theory. Therefore, the optical properties of CrI3 reveal a complex interaction among electronic, phononic and magnetic degrees of freedom, opening many possibilities for its use in 2-Dimensional heterostructures.

scholarly journals Low energy electrodynamics of CrI3 layered ferromagnet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luca Tomarchio ◽  
Salvatore Macis ◽  
Lorenzo Mosesso ◽  
Loi T. Nguyen ◽  
Antonio Grilli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Degrees Of Freedom ◽  
Near Infrared ◽  
Effective Interaction ◽  
Blue Shift ◽  
Ferromagnetic Phase ◽  
Phonon Modes ◽  
Strong Electron ◽  
Spin Lattice ◽  
Electron Phonon Interaction

AbstractWe report on the optical properties from terahertz (THz) to Near-Infrared (NIR) of the layered magnetic compound CrI3 at various temperatures, both in the paramagnetic and ferromagnetic phase. In the NIR spectral range, we observe an insulating electronic gap around 1.1 eV which strongly hardens with decreasing temperature. The blue shift observed represents a record in insulating materials and it is a fingerprint of a strong electron-phonon interaction. Moreover, a further gap hardening is observed below the Curie temperature, indicating the establishment of an effective interaction between electrons and magnetic degrees of freedom in the ferromagnetic phase. Similar interactions are confirmed by the disappearance of some phonon modes in the same phase, as expected from a spin-lattice interaction theory. Therefore, the optical properties of CrI3 reveal a complex interaction among electronic, phononic and magnetic degrees of freedom, opening many possibilities for its use in 2-Dimensional heterostructures.

THERMODYNAMIC CHARACTERISTICS OF Y–Ba–Cu–O TYPE COMPOUNDS IN THE MODEL OF STRONG ELECTRON–PHONON COUPLING

1988 ◽  
Vol 02 (05) ◽  
pp. 837-845 ◽  
Author(s):  
A. A. Golubov
Keyword(s):  
Numerical Solutions ◽  
Low Frequency ◽  
Thermodynamic Characteristics ◽  
Coupling Model ◽  
Phonon Coupling ◽  
Eliashberg Equations ◽  
Phonon Modes ◽  
Strong Electron ◽  
Phonon Spectra ◽  
Electron Phonon Coupling

Based on recently measured phonon density of states of Y–Ba–Cu–O an investigation of the strong electron-phonon coupling model is carried out. The numerical solutions of the real axis Eliashberg equations are obtained for a number of phonon spectra parameters. Isotope shifts of T c , spectral behavior of the pairing energy Δ(ω) and the ratio 2Δ g / T c (where Δ g is the gap edge) are calculated. The model gives a very small oxygen isotope shift for rather moderate values of the electron-phonon coupling constant λ ~ 3. The results strongly suggest the weak coupling with high frequency phonon modes and strong coupling with low frequency modes.

scholarly journals Pressure-induced phase transitions and superconductivity in magnesium carbides

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sooran Kim ◽  
Kyoo Kim ◽  
Jahyun Koo ◽  
Hoonkyung Lee ◽  
Byung Il Min ◽  
...  
Keyword(s):  
High Pressure ◽  
Structure Prediction ◽  
Ambient Pressure ◽  
Physical Property ◽  
Functional Materials ◽  
Phonon Modes ◽  
Strong Electron ◽  
Graphene Layers ◽  
High Pressure Studies ◽  
Out Of Plane

AbstractCrystal structure prediction and in silico physical property observations guide experimental synthesis in high-pressure research. Here, we used magnesium carbides as a representative example of computational high-pressure studies. We predicted various compositions of Mg–C compounds up to 150 GPa and successfully reproduced previous experimental results. Interestingly, our proposed MgC2 at high pressure >7 GPa consists of extended carbon bonds, one-dimensional graphene layers, and Mg atomic layers, which provides a good platform to study superconductivity of metal intercalated graphene nano-ribbons. We found that this new phase of MgC2 could be recovered to ambient pressure and exhibited a strong electron-phonon coupling (EPC) strength of 0.6 whose corresponding superconductivity transition temperature reached 15 K. The EPC originated from the cooperation of the out-of-plane and the in-plane phonon modes. The geometry confinement and the hybridization between the Mg s and C pz orbitals significantly affect the coupling of phonon modes and electrons. These results show the importance of the high-pressure route to the synthesis of novel functional materials, which can promote the search for new phases of carbon-based superconductors.

scholarly journals Strong electron–phonon coupling influences carrier transport and thermoelectric performances in group-IV/V elemental monolayers

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yu Wu ◽  
Bowen Hou ◽  
Ying Chen ◽  
Jiang Cao ◽  
Hezhu Shao ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Carrier Transport ◽  
Group Iv ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Strong Electron ◽  
Relaxation Time Approximation ◽  
Electron Phonon Coupling ◽  
Constant Relaxation Time ◽  
Carrier Transport Properties

AbstractThe interactions between electrons and phonons play the key role in determining the carrier transport properties in semiconductors. In this work, comprehensive investigations on full electron–phonon (el–ph) couplings and their influences on carrier mobility and thermoelectric (TE) performances of 2D group IV and V elemental monolayers are performed, and we also analyze the selection rules on el–ph couplings using group theory. For shallow n/p-dopings in Si, Ge, and Sn, ZA/TA/LO phonon modes dominate the intervalley scatterings. Similarly strong intervalley scatterings via ZA/TO phonon modes can be identified for CBM electrons in P, As, and Sb, and for VBM holes, ZA/TA phonon modes dominate intervalley scatterings in P while LA phonons dominate intravalley scatterings in As and Sb. By considering full el–ph couplings, the TE performance for these two series of monolayers are predicted, which seriously downgrades the thermoelectric figures of merits compared with those predicted by the constant relaxation time approximation.

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