We analyze the paradigmatic competition between intraband and crossband Cooper-pair formation in two-band superconductors, neglected in most works to date. We derive the phase-sensitive gap equations and describe the crossover between the intraband-dominated and the crossband-dominated regimes, delimited by a “gapless” state. Experimental signatures of crosspairing comprise notable gap splitting in the excitation spectrum, non-BCS behavior of gaps versus temperature, as well as changes in the pairing symmetry as a function of temperature. The consequences of these findings are illustrated on the examples of ${\mathrm{MgB}}_2$ and ${\mathrm{Ba}}_{0.6}{\mathrm{K}}_{0.4}{\mathrm{Fe}}_2{\mathrm{As}}_2$.

中文翻译：

---

超导体中的带内配对和带内配对：相互作用的特征和后果

我们分析了两波段超导体中带内和跨带库珀对形成之间的范式竞争，这在迄今为止的大多数工作中都被忽略了。我们推导了相敏间隙方程，并描述了由“无间隙”状态界定的带内支配和跨带支配体制之间的交叉。交叉配对的实验特征包括激发光谱中明显的缺口分裂，缺口的非BCS行为与温度的关系以及配对对称性随温度的变化。这些发现的后果在以下示例中得以说明${\mathrm{镁硼}}_2$ 和 ${巴}_{0.6}{\mathrm{ķ}}_{0.4}{铁}_2{如}_2$。