Ginzburg-Landau theory of vortices in a multi-gap superconductor

M. E. Zhitomirsky (1) , V. -H. Dao (1)

1 SPSMS - UMR 9001 - Service de Physique Statistique, Magnétisme et Supraconductivité

The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling BCS model. The two-gap Ginzburg-Landau theory is, then, applied to investigate various magnetic properties of MgB2 including an upturn temperature dependence of the transverse upper critical field and a core structure of an isolated vortex. Orientation of vortex lattice relative to crystallographic axes is studied for magnetic fields parallel to the c-axis. A peculiar 30-degree rotation of the vortex lattice with increasing strength of an applied field observed by neutron scattering is attributed to the multi-gap nature of superconductivity in MgB2.

Domaines: Supraconductivité [cond-mat.supr-con]

M. E. Zhitomirsky, V. -H. Dao. Ginzburg-Landau theory of vortices in a multi-gap superconductor. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2004, 69, pp.054508. ⟨hal-00007663⟩