The Quantum-Classical Metal

Abstract

In a normal Fermi liquid, Landau's theory precludes the loss of single fermion, quantum coherence in the low energy/temperature limit. For highly anisotropic, strongly correlated metals there is no proof that this remains the case: we propose that quantum coherence for transport in some directions may be lost intrinsically. This should stabilize a novel, qualitatively anisotropic non-Fermi liquid, separated by a novel zero temperature, quantum phase transition from the Fermi liquid state and categorized by the unobservability of certain interference effects. There is compelling experimental evidence for this transition as a function of magnetic field in the metallic phase of the organic conductor (TMTSF)_2PF_6.