Role of spatial disorder in strange metals

We now have a reasonable theory for non-Fermi liquids without quasiparticles in two spatial dimensions: a Fermi surface coupled to a critical boson, with the boson representing a symmetry-breaking order or an emergent collective mode. It was initially proposed that such a non-Fermi liquid could describe the strange metal behavior of correlated electron compounds. But it has now been established that the transport properties of such a non-Fermi liquid are not very different from that of a Fermi liquid: the conservation of momentum in the singular low-energy processes prevents the decay of electrical currents. However, in the presence of spatial disorder, strange metal behavior is possible at low temperatures (T): I will review recent work showing how spatial disorder in the boson-fermion coupling leads to a metal with marginally defined quasiparticles, a T ln(1/T) specific heat, linear-in-T resistivity, an optical conductivity which scales as 1/frequency, and a Planckian scattering rate.