论文标题
二维超导体和超流体的临界温度上的上限更紧密：接近至上
Tighter upper bounds on the critical temperature of two-dimensional superconductors and superfluids: Approaching the supremum
论文作者
论文摘要
我们讨论了二维超导体和超级流体与粒子密度n或填充因子$ν$的临界温度上的标准和更紧密的上限，这是在从正常到超导体到超导体（超级输液）阶段的过渡，由Berezinskii-Kosterlitz-bigning anding anding anding Aryniveriancy（berezinski-kosterlitiant andiverrant）管理。存在超流体密度张量与$ T_C $之间的关系。标准的临界温度上限$ t_c^{\ rm UP1} $是从Glover-Ferrell-Tinkham总规则中获得的光电率，这限制了超流体密度张量的组件。但是，我们表明$ t_c^{\ rm UP1} $仅在低粒子/载体密度的极限下有用，在低粒子/载体密度的限制下，它可能接近关键温度topremum $ t_c^{\ rm sup} $。对于中间和高粒子/载体密度，对于任何给定的相互作用强度，$ t_c^{\ rm up1} $远远超过$ t_c^{\ rm sup} $。我们证明，必须至少考虑超导性（超导性）的阶参数相位波动的全部影响，以在较大范围的密度上建立更紧密的界限。使用重新归一化组，我们获得了相位波动$ T_C $的临界温度至上，并表明它比$ T_C^{\ rm SUP} $比$ T_C^{\ rm up1} $更紧密地绑定到$ t_c^{\ rm sup} $。我们结论说，如果在涉及单个频段系统的实验中超过$ t_c $，则必须调用非BKT机制。
We discuss standard and tighter upper bounds on the critical temperature $T_c$ of two-dimensional superconductors and superfluids versus particle density n or filling factor $ν$, under the assumption that the transition from the normal to the superconducting (superfluid) phase is governed by the Berezinskii-Kosterlitz-Thouless (BKT) mechanism of vortex-antivortex binding and a direct relation between the superfluid density tensor and $T_c$ exists. The standard critical temperature upper bound $T_c^{\rm up1}$ is obtained from the Glover-Ferrell-Tinkham sum rule for the optical conductivity, which constrains the superfluid density tensor components. However, we show that $T_c^{\rm up1}$ is only useful in the limit of low particle/carrier density, where it may be close to the critical temperature supremum $T_c^{\rm sup}$ . For intermediate and high particle/carrier densities, $T_c^{\rm up1}$ is far beyond $T_c^{\rm sup}$ for any given interaction strength. We demonstrate that it is imperative to consider at least the full effects of phase fluctuations of the order parameter for superconductivity (superfluidity) to establish tighter bounds over a wide range of densities. Using the renormalization group, we obtain the critical temperature supremum for phase fluctuations $T_c$ and show that it is a much tighter upper bound to $T_c^{\rm sup}$ than $T_c^{\rm up1}$ for all particle/carrier densities. We conclude by indicating that if the $T_c$ is exceeded in experiments involving single band systems, then a non-BKT mechanism must be invoked.
