![QUANTUM MATERIALS AND DEVICES SEMINARS: Landau`s Fermi liquids in disguise](/++theme++dipc-theme/img/event_image_berdea.png)
Correlated metals, and sometimes even correlated insulators, often display
non-Fermi liquid properties, like single-particle spectra lacking
quasiparticles and very poor, or even absent, metallic charge transport,
coexisting with conventional Fermi liquid behaviour of thermal properties or
quantum oscillations. That Janus-faced character likely entails the existence
of new paradigms of strongly interacting electrons, but, sometimes, it might
simply indicate that the class of Landau`s Fermi liquids is broader and
displays a richer physics than commonly believed.
Here, I will show that, contrary to the common belief, coherent
`quasiparticles` also emerge approaching a Luttinger surface, i.e., the
location within the Brillouin zone of the zeros of the single-particle Green`s
function at zero energy and temperature, just as they do approaching a Fermi
surface, where the Green’s function has instead poles. That occurs despite
the single-particle pseudogap at the Luttinger surface. The microscopic
derivation of Landau’s Fermi liquid theory, leading to the conventional
expression of the low-frequency long-wavelength linear response functions, and
thus of the uniform thermodynamic susceptibilities, works for
`quasiparticles`at a Luttinger surface just like it does for quasiparticles at
a Fermi surface, For instance, `quasiparticles`at a Luttinger surface yield a
standard linear in temperature specific heat, in striking contrast with the
vanishing single-particle density of states. Remarkably, Luttinger`s theorem
entails that the number of `quasiparticles` at a Luttinger surface counts the
number of physical holes, while the number of quasiparticles at the Fermi
surface counts the number of physical electrons.
I will end discussing the surprisingly reach physical behaviour that comes out
of a toy self-energy vaguely inspired by the phenomenology of underdoped
cuprates, and which admits a Luttinger surface either alone or coexisting with
Fermi pockets, and thus unconventional `quasiparticles` coexisting or not with
conventional ones.
References:
M. Fabrizio, arXiv:2105.12528
M. Fabrizio, Physical Review B 102, 155122 (2020)
Host: Miguel A. Cazalilla
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