1998/04/06 by Kyungwha Park, David A. Huse · 1 citation
Materials Science · Mathematics · Physics and Astronomy · #Anisotropy #Condensed matter physics #Geometry #Iron-based superconductors research #Ising model #Lattice (music) #Mathematics #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Rare-earth and actinide compounds #Square (algebra) #Square lattice #Superconductivity #Tetragonal crystal system #Vortex #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.58.9427
published as Phys. Rev. B 58, 9427 (1998) · 15 pages including 2 figures, LaTex
arxiv created 1998/04/06 · openalex publication_date 1998/10/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the stability of the square vortex lattice which has been recently observed in experiments on the borocarbide family of superconductors. Taking into account the tetragonal symmetry of these systems, we add fourfold symmetric fourth-derivative terms to the Ginzburg-Landau (GL) free energy. At Hc2 these terms may be treated perturbatively to lowest order to locate the transition from a distorted hexagonal to a square vortex lattice. We also solve for this phase boundary numerically in the strongly type-II limit, finding large corrections to the lowest-order perturbative results. We calculate the relative fourfold Hc2 anisotropy for field in the xy plane to be 4.5% at the temperature, Tc^\ensuremath\square, where the transition occurs at Hc2 for field along the z axis. This is to be compared to the 3.6% obtained in the perturbative calculation. Furthermore, we find that the phase boundary in the H\ensuremath-T phase diagram has positive slope near Hc2.