Universal dynamics of nematic quantum critical metals

Electronic nematicity – spontaneous quadrupole deformation of the electronic dispersion – has been discovered in a variety of strongly correlated quantum materials. Of special interest are metals near a nematic quantum critical point, such as iron-based superconductors. I will discuss how the non-conservation of a nematic order parameter links long-range quantum fluctuations and short-range anisotropy. This link appears in the nonzero uniform dynamical susceptibility in polarized Raman scattering, and reveals important microscopic details about the iron-based superconductors. The interplay of long- and short- scales also gives rise to a unique form of superconducting pairing and leads to a highly anisotropic superconducting gap that evolves strongly with temperature.