AMPC  Vol.2 No.4 , December 2012
Theory of Electron Density of States of High Temperature Impurity Induced Anharmonic Superconductors
ABSTRACT

The expression for the electron density of states (EDOS) of high temperature superconductors (HTS) has been derived taking the disorder and anharmonicity effects as a central problem. This has been dealt with the help of double time thermodynamic Green’s function theory for electrons via a generalized Hamiltonian which consists of the contribution due to 1) unperturbed electrons; 2) unperturbed phonons; 3) isotopic impurities; 4) anharmonicities (no BCS type Hamiltonian has been taken up in the formulation); and 5) electron-phonon interactions. The renormalization effects and emergence of pairons appears as a unique feature of the theory and dependence of EDOS on impurity concentration and temperature has been discussed in details with special reference to the HTS.


Cite this paper
H. Singh, A. Singh, V. Ashokan and B. Indu, "Theory of Electron Density of States of High Temperature Impurity Induced Anharmonic Superconductors," Advances in Materials Physics and Chemistry, Vol. 2 No. 4, 2012, pp. 249-254. doi: 10.4236/ampc.2012.24037.
References
[1]   J. G. Bednorz and K. A. Muller, “Possible High Tc Superconductivity in the Ba-La-Cu-O System,” Zeits-chrift für Physik B Condensed Matter, Vol. 64, No. 2, 1986, pp. 189-193. doi:10.1007/BF01303701

[2]   G. D. Mahan and J. O. Sofo, “Resistivity and Superconductivity from Anharmonic Pho-nons,” Physical Review B, Vol. 47, No. 13, 1993, pp. 8050-8055. doi:10.1103/PhysRevB.47.8050

[3]   L. R. Testardi, “Structure Instability, Anharmonicity and High-Temperature Superconductivity in A-15-Structure Compounds,” Physical Review B, Vol. 5, No. 11, 1972, pp. 4342-4349. doi:10.1103/PhysRevB.5.4342

[4]   J. Tang, J. Xu, S. Heguri, H. Fukuoka, S. Yamanaka, K. Akai and K. Tanigaki, “Elec-tron-Phonon Interactions of Si100 and Ge100 Superconductors with Ba Atoms Inside,” Physical Review Letters, Vol. 105, No. 17, 2010, Article ID: 176402. doi:10.1103/PhysRevLett.105.176402v

[5]   O. V. Dolgov and A. A. Golubov, “Strong Electron- Phonon Interaction in Multi-band Superconductors,” Phy- sical Review B, Vol. 77, No. 21, 2008, Article ID: 214526. doi:10.1103/PhysRevB.77.214526

[6]   D. N. Zubarev, “Double-Time Green’s Functions in Statistical Physics,” Soviet Physics Uspekhi, Vol. 3, No. 3, 1960, p. 320. doi:10.1070/PU1960v003n03ABEH003275

[7]   K. N. Pathak, “Theory of Anharmonic Crystals,” Physical Review, Vol. 139, No. 5A, 1965, pp. 1569-1580. doi:10.1103/PhysRev.139.A1569

[8]   V. Ashokan, B. D. Indu and A. K. Dimri, “Signature of Electron-Phonon Interaction in High Temperature Super- conductors,” AIP Advances, Vol. 1, No. 3, 2011, Article ID: 032101.

[9]   B. D. Indu, “Theory of Lattice Specific Heat of an Iso- topically Disordered Anharmonic Crystal,” International Journal of Modern Physics B, Vol. 6, No. 7-8, 1990, pp. 1379-1393. doi:10.1142/S021797929000067X

[10]   B. D. Indu, “Enhanced Phonon Density of States in Impure Anharmonic Crystals,” Modern Physics Letters B, Vol. 6, No. 26, 1990, pp. 1665-1672. doi:10.1142/S0217984992001368

[11]   S. H. Pan, E. W. Hudson, K. M. Lang, H. Eisaki, S. Uchida and J. C. Davis, “Imaging the Effects of Individual Zinc Impurity Atoms on Super-conductivity in Bi-Sr-Ca-Cu-O,” Nature, Vol. 403, 2000, pp. 746-750. doi:10.1038/35001534

[12]   S. H. Pan, J. P. O’Neal, R. L. Badzey, C. Chamon, H. Ding, J. R. Engelbrecht, Z. Wang, H. Eisaki, S. Uchida, A. K. Gupta, K. W. Ng, E. W. Hudson, K. M. Lang and J. C. Davis, “Microscopic Electronic Inhomogeneity in the High Tc Superconductor Bi2Sr2CaCu2O8+x,” Nature, Vol. 413, 2001, pp. 282-285. doi:10.1038/35095012

 
 
Top