Unstability of the Fulde-Ferrell State in a d-wave Superconductor by Calculating the Magnetic Penetration Depth at Low temperatures

摘要

We determine the penetration depth of the Fulde-Ferrell State (FF) in a d-wave supercoductor by calculating the electromagnetic nonlocal kernel response function. The behavior of the penetration depth at low temperatures is an important probe to determine the stability of the FF state due to Nernst theorem. Our calculations show that the penetration depth varies linearly with temperature therefore the FF state may not be stable at low temperatures.