Spin-orbit coupling is essential to the quantum-mechanical description of atomic energy levels. Yet its most spectacular consequences are found in the low-energy electronic structure of solids, where this atomic-like interaction plays a key role in the emergence of some of the most unconventional quantum phenomena. In this talk I will show how spin and angle-resolved photoemission spectroscopy, in combination with in-situ doping techniques, can be used to unveil the role of spin-orbit interaction in the emergence of p-wave superconductivity in Sr2RuO4 [1], Rashba and topological spin-splitting in Bi2Se3 [2], and Mott-like insulating behavior in Na2IrO3.

[1] M.W. Haverkort et al., Phys. Rev. Lett. 101, 026406 (2008).
[2] Z.-H. Zhu et al., Phys. Rev. Lett. 107, 186405 (2011).