Iron based superconductors sent material scientists into a renewed excitement reminiscent of the time when the first high-Tc superconductors were discovered 25 years ago. This feature article reviews relationships between structural chemistry and magnetic as well as superconducting properties of iron arsenide compounds, which are outstandingly rich and uniquely coupled. Particular attention is ...

We discuss some experimental signatures associated with the topological structures of unconventional superconductor order parameters of form dx2−y2 + ix, where x=s, px± py, or dxy. Specifically, we study the topological surface states on the s110d and equivalent surfaces of such superconductors which are observable in Andreev tunneling experiments, as well as evaluate the magnetic flux trapped ...

During the past few decades, several new classes of superconductors have been discovered that do not appear to be related to traditional superconductors. The source of the superconductivity of these materials is likely different from the electron-ion interactions that are at the heart of conventional superconductivity. Developing a rigorous theory for any of these classes of materials has prove...

In the fall of 2001, a group of researchers at Aoyama Gakuin University published a report in Nature on a new superconducting material, MgB2 (magnesium boride), which has a critical temperature of 39 K [1], the finding of which sent shock waves around the world. The discovery of superconductivity in Hg traces back to 1911. Since then, various metals and metal compounds have been confirmed to sh...

Irradiation-induced suppression of the critical temperature in high-T c superconductors: Pair breaking versus phase fluctuations Experiments on the irradiation-induced suppression of the critical temperature in high-T c superconductors are analyzed within the mean-field Abrikosov-Gor'kov-like approach. It is shown that the experimental data for YBa 2 Cu 3 O 7−δ single crystals can be quantitati...

FeSe superconductors and their related systems have attracted much attention in the study of iron-based superconductors owing to their simple crystal structure and peculiar electronic and physical properties. The bulk FeSe superconductor has a superconducting transition temperature (Tc) of ~8 K and it can be dramatically enhanced to 37 K at high pressure. On the other hand, its cousin system, F...

When coupling a superconductor to a normal conducting region the physical properties of the system are highly affected by the superconductor. We will investigate the effect of one or two superconductors on the conductance of a ballistic chaotic quantum dot to leading order in the total channel number using trajectory based semiclassics. The results show that the effect of one superconductor on ...

We theoretically study the creep of the inhomogeneous vortex density profile (the Bean state) in superconductors. The low temperatures experimental phenomenology, previously interpreted in terms of “quantum tunnelling” of vortices, is reproduced by Monte Carlo simulations of a purely “classical” vortex model. We demonstrate that a non-zero creep rate in the limit of vanishing temperature is to ...

The equations for the magnon pairing theory of high-temperature copper-oxide-based superconductors are solved and used to calculate several properties, leading to results for specific heat and critical magnetic fields consistent with experimental results. In addition, the theory suggests an explanation of why there are two sets of transition temperatures (T, 90 K and Tc 55 K) for the YBa2Cu306+...

A topological theory of d-wave superconductors is derived in this thesis. Ginzburg-Landau theory describes superconductivity by defining a complex order parameter and applying Landau’s theory for phase transitions. However, there is no local, gauge invariant order parameter for a superconductor and classical order is no appropriate description. Topological order has proven to be a powerful tool...