2017/05/05 by Xue-Yang Song, Chao-Ming Jian, Leon Balents · 2 citations
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.119.216601
published as Phys. Rev. Lett. 119, 216601 (2017) · 17 pages, 6 figures
arxiv created 2017/05/05 · arxiv updated 2017/11/29
Strongly correlated metals comprise an enduring puzzle at the heart of condensed matter physics. Commonly a highly renormalized heavy Fermi liquid occurs below a small coherence scale, while at higher temperatures a broad incoherent regime pertains in which quasi-particle description fails. Despite the ubiquity of this phenomenology, strong correlations and quantum fluctuations make it challenging to study. The Sachdev-Ye-Kitaev(SYK) model describes a 0+1D quantum cluster with random all-to-all four-fermion interactions among N Fermion modes which becomes exactly solvable as N→ ∞, exhibiting a zero-dimensional non-Fermi liquid with emergent conformal symmetry and complete absence of quasi-particles. Here we study a lattice of complex-fermion SYK dots with random inter-site quadratic hopping. Combining the imaginary time path integral with real time path integral formulation, we obtain a heavy Fermi liquid to incoherent metal crossover in full detail, including thermodynamics, low temperature Landau quasiparticle interactions, and both electrical and thermal conductivity at all scales. We find linear in temperature resistivity in the incoherent regime, and a Lorentz ratio L≡ (κρ)/(T) varies between two universal values as a function of temperature. Our work exemplifies an analytically controlled study of a strongly correlated metal.