Separation of transport lifetimes in SrTiO3-based two-dimensional electron liquids

TL;DR

This study reveals a universal two-lifetime behavior in SrTiO3-based 2D electron liquids, showing a divergence at a quantum phase transition, which constrains theories of non-Fermi liquid phenomena.

Contribution

It demonstrates the separation of transport and Hall scattering rates in SrTiO3 interfaces, providing a simple framework for understanding their temperature dependence and critical behavior.

Findings

Transport and Hall scattering rates are separable across different conditions.

Hall scattering rate diverges at a quantum phase transition.

The results impose new constraints on microscopic theories of lifetime separation.

Abstract

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.