非晶态超导体的2△0/(kBTc)和声子谱参量

提出了能够很好地描述非过渡金属无序和非晶态超导体的2Δ₀/(k_BT_c)与声子谱参量之间关系的一个公式:2Δ₀(k_BT_c=4.951-(T₀<ω>^1/2)/A(1/(λω₀)+1/(20λ<ω>)+1/(20<ω>))]。计算了大量已知声子谱的非晶和无序超导体的能隙2Δ₀对T_c的比,结果表明在百分之几的范围内与实验值符合。指出了非过渡金属和合金的非晶态超导体,既可以是一个2Δ₀/(k_BT_c)值远大于BCS理论值(3.53)的强耦合超导体,也可以是一个2Δ₀/(k_BT_c)值比BCS理论值还要小得多的弱耦合超导体。 关键词：

THE 2Δ0/(kBTc) AND THE PARAMETERS OF THE PHONON SPECTRUM FOR AMORPHOUS SUPERCONDUCTORS

In this paper, we propose a formula (2△₀)/(k_BT_c)=4.951-T₀<ω>^1/2/A(1/(λω₀)+1/(20λ<ω>)+1/(20<ω>))], it can describe well the relations between 2△₀/(k_BT_c) and the parameters of the phonon spectrum of disordered and amorphous superconductors for the non-transition metals and their alloys. Here T₀ =0.66K, A =1/5K^1/2, λ is electron-phonon coupling constant, <ω> is the average phonon frequency and ω₀ the high frequency cutoff of the effective phonon spectrum a²F(ω). The values of 2△₀/(k_BT_c) of disordered and amorphous superconductors which have the known parameters of the phonon spectrum have been calculated. Agreement with experiment is within a few percent. We show that the amorphous superconductor of non-transition metals and alloys is either a strong coupling superconductor which has a 2△₀/(k_BT_c) valve much larger than the BCS theory value or a weak coupling superconductor which has a considerable smaller one than the BCS theory value.