Davidson, RichardFu, WenboGeorges, AntoineGu, YingfeiJensen, KristanSachdev, Subir2019-09-112017-04-18Davison, Richard A., Wenbo Fu, Antoine Georges, Yingfei Gu, Kristan Jensen, and Subir Sachdev. 2017. Thermoelectric Transport in Disordered Metals Without Quasiparticles: The Sachdev-Ye-Kitaev Models and Holography. Physical Review B 95: 155131.2469-99502469-9969http://nrs.harvard.edu/urn-3:HUL.InstRepos:41307109We compute the thermodynamic properties of the Sachdev-Ye-Kitaev (SYK) models of fermions with a conserved fermion number Q. We extend a previously proposed Schwarzian effective action to include a phase field, and this describes the low-temperature energy and Q fluctuations. We obtain higher-dimensional generalizations of the SYK models which display disordered metallic states without quasiparticle excitations, and we deduce their thermoelectric transport coefficients. We also examine the corresponding properties of Einstein-Maxwell-axion theories on black brane geometries which interpolate from either AdS4 or AdS5 to an AdS2×R2 or AdS2×R3 near-horizon geometry. These provide holographic descriptions of nonquasiparticle metallic states without momentum conservation. We find a precise match between low-temperature transport and thermodynamics of the SYK and holographic models. In both models, the Seebeck transport coefficient is exactly equal to the Q derivative of the entropy. For the SYK models, quantum chaos, as characterized by the butterfly velocity and the Lyapunov rate, universally determines the thermal diffusivity, but not the charge diffusivity.en-USJournal Article2019-09-1110.1103/physrevb.95.155131