Crossing point of the magnetisation in high-temperature superconductors

Abstract The magnetisation curves M ( H , T ) of the most anisotropic high temperature superconductors cross in a single point M * ( T * ), independently of the magnetic field H that is applied perpendicular to the superconducting planes. This property may be very generally derived from the singular part of the free energy of a two-dimensional (2D) superconductor with fluctuations at T c . Correspondingly, three-dimensional (3D) superconductors have a crossing point in the quantity M / H 1/2 at T c , with an amplitude proportional to the anisotropy ratio γ ≡( m c / m ab ) 1/2 .