Why Magnesium Diboride Is Not Described by Anisotropic Ginzburg-Landau Theory

A. E. Koshelev, A. A. Golubov
2004 Physical Review Letters  
It is well established that the superconductivity in the recently discovered superconducting compound MgB$_{2}$ resides in the quasi-two-dimensional band ($\sigma$-band) and three-dimensional band ($\pi$-band). We demonstrate that, due to such band structure, the anisotropic Ginzburg-Landau theory practically does not have region of applicability, because gradient expansion in the $c$ direction breaks down. In the case of dirty $\pi$-band we derive the simplest equations which describe
more » ... h describe properties of such superconductors near $T_{c}$ and explore some consequences of these equations.
doi:10.1103/physrevlett.92.107008 pmid:15089235 fatcat:sw6lytwdtjg2navjotwj2ovrgy