We present the screening dependence theoretical investigations of the superconducting state parameters, i.e. electron-phonon coupling strength A, Coulomb pseudopotential μ＊, transition temperature To, isotope effect...We present the screening dependence theoretical investigations of the superconducting state parameters, i.e. electron-phonon coupling strength A, Coulomb pseudopotential μ＊, transition temperature To, isotope effect exponent α, and effective interaction strength NoV of some CucZr100-c （C = 25, 30, 33, 35, 40, 45, 50, 55, 57, 60 at.%） binary amorphous alloys by employing the well-known empty core model potential of Ashcroft. Five screening functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are used to study the screening influence on the aforesaid superconducting properties. The transition temperature Tc obtained from the Ichimaru-Utsumi screening function is found to be in excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with the other earlier reported data, which confirms the superconducting phase in the amorphous alloys.展开更多
We present the replacement and modification of the Debye temperature θD by the average phonon frequency （ω） in the Rowell [Solid State Commun. 19 （1976） 1131] linear transition-temperature equation for supercond...We present the replacement and modification of the Debye temperature θD by the average phonon frequency （ω） in the Rowell [Solid State Commun. 19 （1976） 1131] linear transition-temperature equation for superconducting materials. We not only improve Rowell＇s results but also describe the experimental results accurately and consistently for the various superconducting systems which cover the entire range of λ between 0.72 and 2.59. The proposed linear equation of the transition temperature Tc is found to be better and more accurate than those of dain and Kachhava [Can. d. Phys. 58 （1980） 1614].展开更多
The computations of the phonon dispersion curves （PDC） of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in...The computations of the phonon dispersion curves （PDC） of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom （PAA） is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree （H） and Ichimaru-Utsumi （IU） are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.展开更多
A well-known pseudopotential is used to investigate the superconducting state parameters （SSP）, viz., electronphonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and ef...A well-known pseudopotential is used to investigate the superconducting state parameters （SSP）, viz., electronphonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture.展开更多
Effect of rhenium doping is examined in single crystals of MoSe2 viz. MoRe0.005Sel.995, MoReo.o01 Sel.999 and Moo.995Re0.005Se2, which is grown by using the direct vapor transport （DVT） technique. The grown crystals...Effect of rhenium doping is examined in single crystals of MoSe2 viz. MoRe0.005Sel.995, MoReo.o01 Sel.999 and Moo.995Re0.005Se2, which is grown by using the direct vapor transport （DVT） technique. The grown crystals are structurally characterized by X-ray diffraction, by determining their lattice parameters a and c, and X-ray density. Also, the Hall effect and thermoelectric power （TEP） measurements show that the single crystals exhibit a p-type semiconducting nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials.展开更多
文摘We present the screening dependence theoretical investigations of the superconducting state parameters, i.e. electron-phonon coupling strength A, Coulomb pseudopotential μ＊, transition temperature To, isotope effect exponent α, and effective interaction strength NoV of some CucZr100-c （C = 25, 30, 33, 35, 40, 45, 50, 55, 57, 60 at.%） binary amorphous alloys by employing the well-known empty core model potential of Ashcroft. Five screening functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are used to study the screening influence on the aforesaid superconducting properties. The transition temperature Tc obtained from the Ichimaru-Utsumi screening function is found to be in excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with the other earlier reported data, which confirms the superconducting phase in the amorphous alloys.
文摘We present the replacement and modification of the Debye temperature θD by the average phonon frequency （ω） in the Rowell [Solid State Commun. 19 （1976） 1131] linear transition-temperature equation for superconducting materials. We not only improve Rowell＇s results but also describe the experimental results accurately and consistently for the various superconducting systems which cover the entire range of λ between 0.72 and 2.59. The proposed linear equation of the transition temperature Tc is found to be better and more accurate than those of dain and Kachhava [Can. d. Phys. 58 （1980） 1614].
文摘The computations of the phonon dispersion curves （PDC） of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom （PAA） is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree （H） and Ichimaru-Utsumi （IU） are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.
文摘A well-known pseudopotential is used to investigate the superconducting state parameters （SSP）, viz., electronphonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture.
文摘Effect of rhenium doping is examined in single crystals of MoSe2 viz. MoRe0.005Sel.995, MoReo.o01 Sel.999 and Moo.995Re0.005Se2, which is grown by using the direct vapor transport （DVT） technique. The grown crystals are structurally characterized by X-ray diffraction, by determining their lattice parameters a and c, and X-ray density. Also, the Hall effect and thermoelectric power （TEP） measurements show that the single crystals exhibit a p-type semiconducting nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials.
