A variety of superconducting materials exhibit multi-band behavior in a form of multicomponent Fermi surfaces. By using a two-band model with a pair hopping, we explain how the interband coupling affects the physical properties of multi-band superconductors. We determine the temperature dependence of the superconducting gap and the specific heat, which strongly diverge from the BCS-type behavior. The anisotropic gap for the system with the mixed gap symmetry is found. Additionally, the spectral function and density of states are significantly modified by the inter-orbital interactions. The results obtained for different symmetries of the order parameter are in a good agreement with the experimental findings for the iron-based superconductors and other multi-band systems.

多种超导材料以多组分费米表面的形式表现出多频带行为。通过使用具有一对跳变的两频带模型，我们解释了频带间耦合如何影响多频带超导体的物理特性。我们确定了超导间隙和比热的温度依赖性，这与BCS型行为大不相同。发现具有混合间隙对称性的系统的各向异性间隙。另外，轨道间的相互作用显着地改变了光谱函数和状态密度。对于不同阶数对称参数获得的结果与铁基超导体和其他多频带系统的实验结果非常吻合。