Orbital selective spin-fluctuations physics in iron-based superconductors

• Autores: Raquel Fernández Martín
• Directores de la Tesis: Belén Valenzuela Requena (dir. tes.), Laura Fanfarillo (codir. tes.), Amadeo L. Vázquez de Parga (tut. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2021
• Idioma: inglés
• Tribunal Calificador de la Tesis: María José Calderón Prieto (presid.), Isabel Guillamón Gómez (secret.), I. Eremin (voc.), Brian Møller (voc.), Sergio Ciuchi (voc.)
• Programa de doctorado: Programa de Doctorado en Física de la Materia Condensada, Nanociencia y Biofísica por la Universidad Autónoma de Madrid; la Universidad de Murcia y la Universidad de Oviedo
• Materias:
  • Física
    • Electromagnetismo
      • Superconductividad
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • There is no temperature below absolute zero. Researchers have tried to reach this lower limit and this has led to the discovery of new physical phenomena, e.g. superconductivity, which understanding is still unknown. Since its discovery, hundreds of new superconductors have been found. In this Thesis we focus on the family of iron-based superconductors (IBS). Although the crystallographic and electronic structures are very similar in these materials, they present a very different phenomenology. The development of a theory that can explain the complex phenomenology of IBS within a common framework is one of the most important theoretical challenges in the field.

    This Thesis shows how the diverse phenomenology of various families of IBS can be understood within a common framework: the Orbital Selective Spin Fluctuations scenario. Thanks to the orbital selectivity of the magnetic excitations of the system, a spin-orbital interplay arises in the magnetic susceptibility, superconducting gaps and velocity and the scattering rate in the nematic phase of IBS. This model has been extensively used to study the phenomenology of FeSe and 122 systems. The generalization to a five-pockets model, also performed in this Thesis, put the basis to exploit this model to analyze more IBS compounds.

    Beyond IBS, orbital selectivity might also appear in other compounds in which the multiorbital character has a significant role to play. Without doubt, there are numerous avenues where orbital selectivity may play an important role, leaving many possibilities to be explored.