Speaker
Peter Schauss
(Princeton University)
Description
Probing the charge transport properties of quantum materials
can reveal their unique microscopic properties. Weakly
interacting systems such as Fermi liquids are well described
by semiclassical Boltzmann transport, but strong
interactions blur the particle-like behavior of charge
carriers causing this picture to break down. Transport in
strongly interacting quantum systems is poorly understood,
but exhibits interesting phenomenology in many real
materials. In our work, we experimentally study charge
conductivity in the Fermi-Hubbard model. Using a quantum gas
microscope, we impose a density modulation on a uniform
system of ultracold 6Li in a 2D optical lattice and observe
this modulation decay due to charge diffusion. We find that
the decay can be described by a hydrodynamic model and
extract the momentum relaxation rate and diffusion constant
for a range of temperatures. We determine the conductivity
from the diffusion constant using the Nernst-Einstein
relation. We observe that the resistivity scales linearly
with temperature and shows no sign of saturation for
temperatures ranging from near the super-exchange energy
scale to the bandwidth. These anomalous behaviors are
characteristic of bad metals.
