London Penetration Depthin λ(T) in Type 1.5 Superconductor by Ginzburg-Landau Approach

The London penetration depth is the distance to which a magnetic field penetrates into a superconductor and becomes equal to 0.367879 times that of the magnetic field at the surface of the superconductor. The type 1.5 superconductor is the new type of superconductor that the value of Ginzburg-Landau parameter is between the type I and type II superconductor. In this paper, the London penetration depth of type 1.5 superconductor is studied by Ginzburg-Landau approach. The system of free energy of type 1.5 superconductor is assumed by modified the free energy of two-band model and theof type 1.5 superconductor is derived analytically. Finally, the temperature dependence of London penetration depth is investigated.