2 research outputs found
Breakdown of Fermi-liquid theory in a cuprate superconductor
The behaviour of electrons in solids is remarkably well described by Landau's
Fermi-liquid theory, which says that even though electrons in a metal interact
they can still be treated as well-defined fermions, called ``quasiparticles''.
At low temperature, the ability of quasiparticles to transport heat is strictly
given by their ability to transport charge, via a universal relation known as
the Wiedemann-Franz law, which no material in nature has been known to violate.
High-temperature superconductors have long been thought to fall outside the
realm of Fermi-liquid theory, as suggested by several anomalous properties, but
this has yet to be shown conclusively. Here we report on the first experimental
test of the Wiedemann-Franz law in a cuprate superconductor,
(Pr,Ce)CuO. Our study reveals a clear departure from the universal law
and provides compelling evidence for the breakdown of Fermi-liquid theory in
high-temperature superconductors.Comment: 7 pages, 3 figure