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.

[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