Strongly correlated materials close to a Mott metal-to-insulator transition frequently display properties at odds with Landau’s Fermi Liquid Theory, most notably the absence of quasiparticle peaks in the single-particle spectrum. Strikingly, such 'non-Fermi liquid' features are often accompanied by other conventional Fermi liquid properties, like quantum oscillations in a magnetic field, which are characteristics of Fermi surfaces, linear in temperature specific heat, Pauli-like paramagnetism, etc... Such Janus-faced character of supposedly non-Fermi liquid materials prompted theorists to search for new paradigms of strongly correlated systems beyond Fermi liquids.
A SISSA study, published in Nature Communications, shows that the lack of quasiparticle signals in the single-particle spectrum does not necessarily imply that Landau’s quasiparticles do not exist. Indeed, the work demonstrates that even a single-particle pseudo gap can hide well defined quasiparticles yielding conventional Fermi liquid properties. The research, carried out by Michele Fabrizio and financially supported by ERC Advanced Grant FIRSTORM, thus shows that the class of Landau’s Fermi Liquids is much wider than conventionally believed.
Image: Julien Bobroff