Relativistic Theory of Superconductivity

Relativistic effects in materials containing heavy atoms pervade many areas of condensed-matter physics [1-4]. The present chapter is devoted to the theory of relativistic effects in a particularly interesting class of materials, namely superconductors and other superfluids [5-9]. At its present stage that theory is limited to single-particle effects (on the level of the Dirac equation); a relativistic description of the particle-particle interaction is not attempted. However, already on the singleparticle level several unexpected relativistic phenomena in superconductors emerge, among them a novel type of spin-orbit coupling, present in superconductors only. The origin and the physics of these phenomena are discussed in this contribution.