Pairing state symmetries of high-Tc superconductors: a comparative study using two Ginzburg–Landau models

Abstract

An attempt has been made to resolve the issue regarding the pairing symmetry of high-Tc superconducting materials (cuprates). The properties of high-Tc superconductors, which are the signatures of the pairing symmetry of these materials, arebeing calculated by using the anisotropic s-wave Ginzburg–Landau (GL) theory, i.e. theanisotropic single-order parameter GL theory (ASGL), and is compared with thosecalculated in a recent work (Karmakar and Dey 2008 J. Phys.: Condens. Matter 20 255218)by the isotropic d-wave GL theory involving mixed symmetry states of the orderparameters, i.e. the isotropic two-order parameter GL theory (TIGL), over the entire rangeof applied magnetic field and temperature for arbitrary values of the GL parameterκ andvortex lattice symmetry. The results are further compared with suitable experimental data on the high-Tc superconductingcuprate YBa2Cu3O7−δ. It has been found that the TIGL model definitely gives a better match with the experimentaldata and is thus more suitable to describe the pairing state symmetries of the high-Tc superconducting cuprates.