Screening dependence of superconducting state parameters of Cu–Zr metallic glasses

Abstract

The screening dependence of superconducting state parameters (λ, µ*, T c , α and N 0 V) of nine metallic glasses of the Cu-Zr system has been studied in the BCS-Eliashberg-McMillan framework by employing five forms of dielectric screening function in conjunction with Ashcroft's potential. It is observed that the electron-phonon coupling strength (λ) and transition temperature (T c ) are quite sensitive to the form of the dielectric screening, whereas the Coulomb pseudopotential (µ*), isotope effect exponent (α ) and effective interaction strength (N 0 V) show weak dependences on screening function. The RPA form of dielectric screening is observed to yield the best results for all the glasses of the Cu-Zr system studied in the present work. Present computations yield almost linear variation of T c with concentration x of Cu in the Cu-Zr system, which is in agreement with the experimental data. A linear T c equation is proposed by fitting the present results for RPA screening, which is in conformity with other results for the experimental data.

Superconducting state parameters of binary metallic glasses

“…Perhaps only exceptions in the results of the T C of the divalent Be based metallic glasses where high T C is observed likely to be due to unusually high Debye temperature of Be metallic elements. The lower values of T C for Zr 35 20 Sn 80 metallic glasses may be due to the electron transfer between two metallic elements. The increase in T C has also been attributed to the excitonic mechanism resulting from the granular structure separated by semiconducting or insulating materials [1].…”

“…The Ashcroft's empty core (EMC) model potential is a simple one-parameter model potential [28], which has been successfully found for various metallic complexes [5][6][7][8][9][10][11][12][13][14][15][18][19][20][21][22][23][24][25][26][27]. When used with a suitable form of dielectric screening functions, this potential has also been found to yield good results in computing the SSPs of metallic glasses [5][6][7][8][9][10][11][12][13][14][15][18][19][20][21][22][23][24][25][26][27] 25 metallic glass, the model potential parameter C is fitted with the experimental data of the electron-phonon coupling strength λ, which came from the experimental tunneling data [37]. After fitting the model potential parameter C , same C is then used in the computation of the SSPs of binary metallic glasses.…”

“…Experiments also show that the superconducting transition temperature T C is grater for amorphous metals than for crystals, which also depends on the composition of the metallic element in the crystalline as well as amorphous phases . Though the pseudo-potential theory is found very successful in studying the various properties of metallic glasses, there have been very few random attempts to study the superconducting state parameters (SSPs) of binary metallic glasses based on model potential [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The application of a pseudo-potential to a binary metallic glass involves the assumption of pseudoions with average properties, which are assumed to replace two types of ions in the binary systems.…”

“…The theoretical investigation of the SSPs of Cu-Zr metallic glasses has been reported by Sharma et al. [18][19][20]. In most of these studied, Ashcroft's empty core (EMC) model potential [28] is adopted in the calculation.…”

Superconducting state parameters of La100-C GaC binary metallic glasses

“…The study on SSP of Cu-Zr binary metallic glasses was made by Sharma et al [20][21][22]. The SSP of Be-Al metallic glass has been reported by Sharma and co-workers [23,24].…”