Superconductivity is an amazing phenomena. Beyond the eye-popping demos and promises of floating trains, it is a macroscopic manifestation of pure quantum physics. Where most quantum effects are smothered by thermal energy even at the lowest of temperatures, superconductivity brings the strangeness of quantum mechanics to reasonably accessible temperatures. An while it does have applications in terms of effecient charge transfer and the production of powerful magnetic fields, this is not why we study it. The mystery of its origin, oddness of its effects, and beauty of its consequences drives us to delve into the richness of this amazing phenomena.
One key player in the physics of these exotic superconductors appears to be magnetism. Magnetism is a constant presence in the phase diagrams of exotic superconductors and appears to couple to the superconducting transition in some interesting ways. The details of the connection remain unknown, but it is clear that magnetism, either through static order, fluctuations, or both, is an important aspect of the crystalline environments which foster superconductivity.
Through the tool of neutron scattering I investigate this connection across an array or different compounds using a variety of techniques. In this thesis, I conclude on the role of phase separation in superconducting KyFe1.6+xSe2 using neutron diffraction, perform a survey of magnetic excitations across the superconducting phase diagram in NaFe1−xCoxAs with neutron time-of-flight spectroscopy, and reveal new magnetic properties of the old heavy fermion superconductor UPt3 via more traditional neutron measurements.