Manipulation of superconductivity in iron-based superconductors
Abstract: The electronic nematic state has become one of the hottest topics in the research of quantum materials. The most intriguing part of this phase is the correlation effects: electrons in the system are correlated and organize themselves into a unidirectional phase – a quantum version of liquid crystals, with only rotation symmetry broken. Although proposed decades ago, this phase was observed only recently in iron superconductors, cuprates, heavy fermion, and several other systems. I will review the properties of the superconductivity and the nematic phases in iron superconductors. Focused on the orbital order induced in the nematic phase, I will discuss how the uniaxial strain can manipulate the properties of SC. Our calculation shows that not only Tc is enhanced, but the gap structure becomes a mixture of nearly degenerate s and d-wave states by increasing the external strain.