First-order superconducting transition in the inter-band model

• The inter-band phase diagram shows a 1st-order transition induced by V   for T>0T>0.
• The excitations spectra indicates the mechanism of 1st-order transition.
• We perform the Maxwell construction to calculate the 1st-order transition line.
• The ratio r=kBTc/Vr=kBTc/V shows a universal behavior for several attractive interactions.

The comprehension about the theoretical features of superconductivity is an interesting and fundamental topic in condensed matter physics. Several theoretical proposals were considered to describe the new classes of superconducting compounds and alloys. In this work we propose to study a non-conventional superconducting system where the Cooper pairs are formed by fermions from different bands described via two band model with hybridization. In this inter-band scenario we find a first-order phase transition at low temperatures and we observe a tricritical point in the phase diagram. In our description, the control parameter is the hybridization that can be tuned by external pressure. This fact indicates the possibility to observe discontinuities in the SC gap amplitude through applying pressure on the system.