>Almost 70 years ago Russian physicist Lev Landau and his collaborators introduced an incredibly successful conjecture, now known as Landau Fermi liquid theory, to try to understand electron interactions within metals.
>Physicists have discovered an entire zoo of quasiparticles in solid materials with names such as phonons, magnons, spinons, holons and plasmons.
>By thinking of the collective actions of electrons as quasiparticles, physicists have made testable predictions that have been verified time and again in experiments on metals such as gold, silver, copper and aluminum.
>In recent years physicists have found a dozen or more materials that are clearly metals, in the sense that their electrical resistivity decreases with decreasing temperature, but that are not Fermi liquids. These “strange metals” have resistivity at low temperatures that is linearly proportional to temperature—that is, their resistivity varies with the actual temperature rather than with the square of the temperature.
>Scientists have observed superconductivity emerging in multiple families of strange metals at relatively high temperatures.