Superconductivity has again become a challenge following the discovery of unconventional superconductivity. Resistance-free currents have been observed in heavy-fermion materials, organic conductors and copper oxides. The discovery of superconductivity in a single crystal of UGe2, ZrZn2 and URhGe revived the interest in the coexistence of superconductivity and ferromagnetism. The experiments in...

Chiral superconductivity, which breaks time-reversal symmetry, can exhibit a wealth of fascinating properties that are highly sought after for nanoscience applications. We identify doped graphene monolayer as a system where chiral superconductivity can be realized. In this material, a unique situation arises at a doping where the Fermi surface is nested and the density of states is singular. In...

A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the s...

This lecture gives a basic introduction into some aspects of the unconventional superconductivity. First we analyze the conditions to realize unconventional superconductivity in strongly correlated electron systems. Then an introduction of the generalized BCS theory is given and several key properties of unconventional pairing states are discussed. The phenomenological treatment based on the Gi...

The widely held notion that high-temperature superconductivity originates in the cuprate-planes is proven to be faulty. In the cuprates such as YBa2Cu3O7, we argue that the superconductivity resides in the BaO layers. This superconductivity is s-wave, not d-wave, in the bulk. The trio of ruthenate compounds, doped Sr2YRuO6, GdSr2Cu2RuO8, and Gd2−zCezSr2Cu2RuO10 all superconduct in their SrO lay...

Dome-shape superconductivity phase diagram can commonly be observed in cuprateand iron-based systems via tuning parameters such as charge carrier doping, pressure, bond angle, and etc. We report doping electrons from transition-metal elements (TM = Co, Ni) substitution can induce high-Tc superconductivity around 35 K in Ca0.94La0.06Fe2As2, which emerges abruptly before the total suppression of ...

HISTORY OF HIGHTEMPERATURE SUPERCONDUCTIVITY After superconductivity was discovered by Onnes in 1911, many superconductors were discovered and the critical temperature rose year by year. More than 2000 superconducting materials had been discovered by 1975, and the critical temperature had reached 22.3 K with the discovery of Nb3Ge in 1973. After that, however, no higher critical temperature was...