  Deviations from Landau Fermi liquid behavior are ubiquitous features of the
normal state of unconventional superconductors. Despite several decades of
investigation, the underlying mechanisms of these properties are still not
completely understood. In this work, we show that two-dimensional electron
liquids at SrTiO3/RTiO3 (R = Gd or Sm) interfaces reveal strikingly similar
physics. Analysis of Hall and resistivity data show a clear separation of
transport and Hall scattering rates, also known as "two-lifetime" behavior.
This framework gives a remarkably simple and general description of the
temperature dependence of the Hall coefficient. Distinct transport lifetimes
accurately describe the transport phenomena irrespective of the nature of
incipient magnetic ordering, the degree of disorder, confinement, or the
emergence of non-Fermi liquid behavior. The Hall scattering rate diverges at a
critical quantum well thickness, coinciding with a quantum phase transition.
Collectively, these results introduce new constraints on the existing
microscopic theories of lifetime separation and point to the need for unified
understanding.
