2003/04/16 by G. P. Mikitik, Ernst Helmut Brandt, E. H. Brandt
Engineering · Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Superconducting Materials and Applications #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.68.054509
15 pages, 8 figures
arxiv created 2003/04/16 · openalex publication_date 2003/08/07 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The vortex-lattice melting line in three-dimensional type-II superconductors with pinning is derived by equating the free energies of the vortex system in the solid and liquid phases. We account for the elastic and pinning energies and the entropy change that originates from the disappearance of the phonon shear modes in the liquid. The pinning is assumed to be caused by point defects and to be not too strong so that the melting line lies inside the so-called bundle-pinning region. We show that the derived equation for the melting line is equivalent to some Lindemann criterion, which however differs from that used previously. Estimating the effect of pinning on the entropy jump at melting, we find the upper critical point of the melting line from the condition that this jump vanishes. We also consider the H\ensuremath-T phase diagrams of type-II superconductors for different strengths and types of pinning and analyze the two recently discussed scenarios how the melting line and the order-disorder line merge.