EFFECT OF ORBITAL QUANTIZATION ON CRITICAL FIELD OF TYPE-2 SUPERCONDUCTORS

We discuss the effect of the discreteness of the Landau levels on the upper critical field of a type-II superconductor. At T=0°K an ideal superconductor will remain superconducting in an arbitrarily large magnetic field. However, the high-field state is destroyed by a minute amount of impurity scattering or by a small misalignment of up- and down-spin Landau levels. The residual effects are (a) a small shift in the low-temperature critical field [ΔHc2Hc2(kFξ0)-1] and (b) oscillatory structure in the transition temperature Tc2(H) for temperatures Tωc2π2k. © 1968 The American Physical Society.