Research

“What is the mechanism of superconductivity” is one of the most exciting question in physics nowadays. Conventional superconductors are those that can be explained by electron-phonon interaction described by BCS theory. Unconventional superconductors can not be explained by phonon-exchange interaction by the BCS theory, so we do not know neither the mechanism nor the particle-exchange interaction. A common thing of these unconventional superconductivity is that in its phase diagrams it can be find a magnetic order either coexistent or nearby the superconducting phase and so spin fluctuations could be a perfect candidate to be the exchange interaction promoting the formation of Cooper pairs.

Iron superconductors are an example of this unconventional superconductivity. The discovery of iron superconductors has opened a new window in the study of superconductivity. They are high Tc superconductors and multiorbital systems. They present a strong interplay between the spin and the orbital degrees of freedom. An example is the nematic phase which origin has been one of the most controversial topics in this field. There are two candidates to explain the origin of the nematic phase, spin fluctuations or orbital fluctuations. In addition, it is postulated that these fluctuations could be the main candidates to explain the mechanism of superconductivity. So, answering the question about the origin of the nematic phase could help to discover the answer of the question about the origin of the superconducting phase.

Outreach