By: Miguel Araújo
From: Universidade de Évora
At: Instituto de Investigação Interdisciplinar, Anfiteatro
Some of the main properties of the recently discovered iron pnictide superconductors are reviewed. These are high temperature multiband superconductors with a fairly complex Fermi surface exhibiting several electron and hole sheets.Â While no microscopic theory of superconductivity exists yet, some experiments suggest a novel pairing symmetry, the so-called sign-reversed s-wave. We present a theory of Andreev spectroscopy whichÂ takes into account the splitting of the incident electron's probability amplitude amongÂ several conduction bands in the superconductor. Novel surface Andreev bound statesÂ at finite excitation energy which disperse with transverse momentum are predicted.
A study of the single vortex structure is also presented for the sign-reversed s-wave scenario. Sharply localized Matricon-Caroli-deGennes core states at finite energy are found. Finite size effects on T_c are also briefly discussed.