Amit Kumar Khaskalam - Academia.edu (original) (raw)
Related Authors
Indian Institute of Engineering Science and Technology, Shibpur
Uploads
Papers by Amit Kumar Khaskalam
Materials Science Forum, 1996
ABSTRACT
physica status solidi (b), 1998
ABSTRACT
Physica Status Solidi B-basic Solid State Physics - PHYS STATUS SOLIDI B-BASIC SO, 1998
ABSTRACT
Bulletin of Materials Science, 1997
We have investigated the effects of oxygen deficiency (6) on the transition temperature (To) of (... more We have investigated the effects of oxygen deficiency (6) on the transition temperature (To) of (Sin, Er)Ba2CU3OT_ ~ superconductors by incorporating the effects of the two dimensional (2I)) acoustic phonons and plasmons in the framework of strong coupling theory. The proposed approach for yttrium cuprates properly takes care of the double CuO 2 plane in a unit cell and has been found earlier to be successful in describing the pairing mechanism as well as the variation of T c with 6 in YBa2CU3OT_ 6 system. The coupling strength (2), the screening parameter (/~*) and the two dimensional acoustic phonon (plasmon) energy hco (oJ +) as a function of oxygen deficiency is worked out. Finally, the transition temperature is evaluated and is found to be consistent with the earlier experimental data on yttrium euprates. Thus, coupled phonon-plasmon mechanism is adequate to understand the nature of pairing mechanism and oxygen deficiency dependence of transition temperature in 90 K (Sm, Er) Ba 2 Cu 3 0 7-6 superconductors.
Bulletin of Materials Science, 1996
The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discusse... more The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling theory. An interaction potential has been developed for the layered structure with two conducting CuO2(a-b) layers in a unit cell. The interaction potential propcrly takes care ofelectron electron, electron phonon and electron-plasmon interactions. Furthermore, the electron phonon coupling parameter (2), the modified Coulomb repulsive parameter (~:*t and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting transition temperature (T~J is then evaluated by using these coupling parameters and obtained T~ = 9502)K for Y(Yb)Ba2Cu30~ , superconductors with ¢¢, = 0-0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory. The result deduced on the variation of T~ with 6 are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed.
Bulletin of Materials Science, 1998
We have investigated theoretically the effect of oxygen deficiency (6) on normal state resistivit... more We have investigated theoretically the effect of oxygen deficiency (6) on normal state resistivity ~0) as well as its temperature dependence in YBa2CU3OT_ ~ superconductors. This has been based on a potential which incorporates the structure factors and various interactions for double two-dimensional (2-D) conducting CuO 2 plane. Using the Coulomb and electron-phonon terms of the interaction potential, we have then worked out the coupling strength (~) for neighbouring electrons linked via 2-D acoustic phonons (hw_). Furthermore, the scattering time (Z'e_ph) due to electron-phonon interaction is deduced. The variations in "Ke_ph and Pe-ph are studied with oxygen deficiency (¢~) which is in the range of 0-0 < 6 < 1.0, and the results thus obtained are found to be consistent with the earlier reported data. The residual resistivity P0 obtained by extrapolation from experimental data together with Pe-ph will predict the nearly-linear behaviour of normal state resistivity at temperatures (T) [90 < T<300 K] in YBa2Cu307_ ~ superconductors.
Materials Science Forum, 1996
ABSTRACT
physica status solidi (b), 1998
ABSTRACT
Physica Status Solidi B-basic Solid State Physics - PHYS STATUS SOLIDI B-BASIC SO, 1998
ABSTRACT
Bulletin of Materials Science, 1997
We have investigated the effects of oxygen deficiency (6) on the transition temperature (To) of (... more We have investigated the effects of oxygen deficiency (6) on the transition temperature (To) of (Sin, Er)Ba2CU3OT_ ~ superconductors by incorporating the effects of the two dimensional (2I)) acoustic phonons and plasmons in the framework of strong coupling theory. The proposed approach for yttrium cuprates properly takes care of the double CuO 2 plane in a unit cell and has been found earlier to be successful in describing the pairing mechanism as well as the variation of T c with 6 in YBa2CU3OT_ 6 system. The coupling strength (2), the screening parameter (/~*) and the two dimensional acoustic phonon (plasmon) energy hco (oJ +) as a function of oxygen deficiency is worked out. Finally, the transition temperature is evaluated and is found to be consistent with the earlier experimental data on yttrium euprates. Thus, coupled phonon-plasmon mechanism is adequate to understand the nature of pairing mechanism and oxygen deficiency dependence of transition temperature in 90 K (Sm, Er) Ba 2 Cu 3 0 7-6 superconductors.
Bulletin of Materials Science, 1996
The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discusse... more The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling theory. An interaction potential has been developed for the layered structure with two conducting CuO2(a-b) layers in a unit cell. The interaction potential propcrly takes care ofelectron electron, electron phonon and electron-plasmon interactions. Furthermore, the electron phonon coupling parameter (2), the modified Coulomb repulsive parameter (~:*t and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting transition temperature (T~J is then evaluated by using these coupling parameters and obtained T~ = 9502)K for Y(Yb)Ba2Cu30~ , superconductors with ¢¢, = 0-0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory. The result deduced on the variation of T~ with 6 are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed.
Bulletin of Materials Science, 1998
We have investigated theoretically the effect of oxygen deficiency (6) on normal state resistivit... more We have investigated theoretically the effect of oxygen deficiency (6) on normal state resistivity ~0) as well as its temperature dependence in YBa2CU3OT_ ~ superconductors. This has been based on a potential which incorporates the structure factors and various interactions for double two-dimensional (2-D) conducting CuO 2 plane. Using the Coulomb and electron-phonon terms of the interaction potential, we have then worked out the coupling strength (~) for neighbouring electrons linked via 2-D acoustic phonons (hw_). Furthermore, the scattering time (Z'e_ph) due to electron-phonon interaction is deduced. The variations in "Ke_ph and Pe-ph are studied with oxygen deficiency (¢~) which is in the range of 0-0 < 6 < 1.0, and the results thus obtained are found to be consistent with the earlier reported data. The residual resistivity P0 obtained by extrapolation from experimental data together with Pe-ph will predict the nearly-linear behaviour of normal state resistivity at temperatures (T) [90 < T<300 K] in YBa2Cu307_ ~ superconductors.