论文标题
伦敦穿透深度各向异性的温度依赖性具有各向异性阶参数的超导体
Temperature dependence of London penetration depth anisotropy in superconductors with anisotropic order parameters
论文作者
论文摘要
我们研究各向异性阶参数对伦敦穿透深度各向异性$γ_λ（T）$的温度依赖性的影响。在MGB $ _2 $之后，这种依赖性通常归因于超导体中多波段费米表面上的不同差距。但是，我们发现，各向异性参数也可能取决于温度，也可以在具有各向异性顺序参数$δ（t，k_f）$的一个带材料中，给出了一些此类示例。我们还发现，对于不同的阶参数，可以通过D. Einzel，J。Low Temp提出的插值来很好地表示$δ（t）/δ（0）$的温度依赖性。 Phys，{\ bf 131}，1（2003），它大大简化了$γ_λ（t）$的评估。特别感兴趣的是两个对称性的混合顺序参数，其中$γ_λ（t）$可能会在两个阶段的一定相对权重以最大值。另外，在这种情况下，我们发现比率$δ_{max}（0）/t_c $可能超过1.76的弱耦合极限。但是，它并不意味着强烈的耦合，而是由于$δ$的各向异性角变化所致。
We study the effects of anisotropic order parameters on the temperature dependence of London penetration depth anisotropy $γ_λ(T)$. After MgB$_2$, this dependence is commonly attributed to distinct gaps on multi-band Fermi surfaces in superconductors. We have found, however, that the anisotropy parameter may depend on temperature also in one-band materials with anisotropic order parameters $Δ(T,k_F)$, a few such examples are given. We have found also that for different order parameters, the temperature dependence of $Δ(T)/Δ(0)$ can be represented with good accuracy by the interpolation suggested by D. Einzel, J. Low Temp. Phys, {\bf 131}, 1 (2003), which simplifies considerably the evaluation of $γ_λ(T)$. Of particular interest is mixed order parameters of two symmetries for which $γ_λ(T)$ may go through a maximum for a certain relative weight of two phases. Also, for this case, we find that the ratio $Δ_{max}(0)/T_c$ may exceed substantially the weak coupling limit of 1.76. It, however, does not imply a strong coupling, rather it is due to significantly anisotropic angular variation of $Δ$.
