scholarly journals Electron-phonon interaction and ultrasonic attenuation in the ruthenate and cuprate superconductors

2001 ◽  
Vol 65 (1) ◽  
Author(s):  
M. B. Walker ◽  
M. F. Smith ◽  
K. V. Samokhin
Keyword(s):  
Cuprate Superconductors ◽  
Ultrasonic Attenuation ◽  
Phonon Interaction ◽  
Electron Phonon Interaction

ELECTRONIC THEORY FOR ELECTRON-DOPED CUPRATE SUPERCONDUCTORS: d-WAVE SUPERCONDUCTIVITY AND THE PHASE DIAGRAM

2000 ◽  
Vol 14 (29n31) ◽  
pp. 3555-3560
Author(s):  
D. MANSKE ◽  
I. EREMIN ◽  
K. H. BENNEMANN
Keyword(s):  
Cuprate Superconductors ◽  
Narrow Range ◽  
Spin Fluctuation ◽  
Flat Band ◽  
Superconducting Transition ◽  
Phonon Interaction ◽  
Pairing Mechanism ◽  
Lattice Disorder ◽  
Electron Phonon Interaction ◽  
The One

Using the one-band Hubbard Hamiltonian we determine various basic properties of the electron-doped cuprate superconductor Nd 2-x Ce x CuO 4 for a spin-fluctuation-induced pairing mechanism. We find a narrow range of superconductivity and, most importantly, like for hole-doped cuprates dx2-y2 -symmetry for the superconducting order parameter. The superconducting transition temperatures Tc(x) for various electron doping concentrations x are calculated to be much smaller than for hole-doped cuprates due to the different energy dispersion and a flat band well below the Fermi level. We find that lattice disorder may sensitively distort the dx2-y2 -symmetry via electron-phonon interaction yielding a finite isotope exponent α0.

Charge Transport and Ultrasonic Properties of La1/3Sr2/3Fe0.95Co0.05O3Perovskite

2012 ◽  
Vol 482-484 ◽  
pp. 819-823
Author(s):  
Hui Kong ◽  
Wei Dai ◽  
Shuai Shao
Keyword(s):  
Single Phase ◽  
Ultrasonic Attenuation ◽  
Charge Ordering ◽  
Simultaneous Occurrence ◽  
Phonon Interaction ◽  
Strong Electron ◽  
Electron Phonon Interaction ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Ordering Transition

The longitudinal ultrasonic velocity (V) and attenuation at a frequency of 10MHz have been measured in single-phase polycrystalline La1/3Sr2/3Fe0.95Co0.05O3 from 20K to 300K. The temperature dependence of resistivity indicates that La1/3Sr2/3Fe0.95Co0.05O3 undergoes charge ordering transition at TCO. A dramatic increase in V is observed at TCO, which is accompanied by a sharp peak in attenuation. This simultaneous occurrence of resistivity and ultrasonic anomalous features implies extremely strong electron-phonon interaction, which is due to the the Jahn-Teller effect of high-spin Fe4+. Below TCO, another softening in V accompanied by a wide ultrasonic attenuation peak is observed. The analysis of the results suggests that these anomalies may correspond to the breathing-type distortion of Fe-O octahedron.

Impurity induced renormalized phonon spectrum of cuprate superconductors

2018 ◽  
Vol 32 (22) ◽  
pp. 1850237 ◽  
Author(s):  
Anushri Gupta ◽  
Sanjeev K. Verma ◽  
Anita Kumari ◽  
B. D. Indu
Keyword(s):  
Cuprate Superconductors ◽  
Potential Problem ◽  
High Temperature Superconductors ◽  
Many Body ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Many Body Theory ◽  
Anharmonic Lattice ◽  
The Many ◽  
Body Theory

The potential problem of anharmonic lattice vibrations in high-temperature superconductors (HTS) using the most suitable Born–Mayer–Huggins (BMH) potential has been taken up to investigate the renormalized phonon density of states (RPDOS). In order to develop the suitable results, the many body theory using quantum dynamical approach of Green’s function (GF) via an almost complete Hamiltonian (without using BCS type Hamiltonian) has been incorporated which includes harmonic electron and phonon Hamiltonian, electron–phonon interaction Hamiltonian, anharmonic and defect Hamiltonian. The derivation of anharmonic phonon GF for modified form of BMH potential enables to evaluate the renormalized and perturbed mode phonon frequencies of solids. The expressions obtained for the RPDOS can be resolved into diagonal and nondiagonal parts of which the nondiagonal part chiefly depends on impurities and disappears in pure crystals. A large number of new features are investigated in the light of this formulation followed by the numerical analysis for the energy spectrum of representative cuprate HTS YBa2Cu3O[Formula: see text]. The inclusion of defects, anharmonicities and electron–phonon interactions in the cuprate superconductors substantially modifies the scenario of RPDOS and reveals a large number of unexplained peaks in the spectrum.

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