High-Tc cuprates – story of two electronic subsystems

Abstract

Measured transport properties of three representative cuprates are reproduced within the paradigm of two electron subsystems, itinerant and localized. The localized subsystem evolves continuously from the Cu 3d[Formula: see text] hole at half-filling and corresponds to the (pseudo)gapped parts of the Fermi surface. The itinerant subsystem is observed as a pure Fermi liquid (FL) with material-independent universal mobility across the doping/temperature phase diagram. The localized subsystem affects the itinerant one in our transport calculations solely by truncating the textbook FL integrals to the observed (doping- and temperature-dependent) Fermi arcs. With this extremely simple picture, we obtain the measured evolution of the resistivity and Hall coefficients in all three cases considered, including LSCO which undergoes a Lifshitz transition in the relevant doping range, a complication which turns out to be superficial. Our results imply that prior to evoking polaronic, quantum critical point, quantum dissipation, or even more exotic scenarios for the evolution of transport properties in cuprates, Fermi-surface properties must be addressed in realistic detail.

Based on now well-established universal transport and optical conductivity properties, we show that the phenomenology of cuprates across the phase diagram is fully captured by the charge conservation relation: 1 + p = nloc + neff with the superfluid density that simply corresponds to: ρₛ = neff ‧ (Oₛ ‧ nloc) where p is doping, neff is the carrier density, which can be directly determined experimentally, while OS is a compound-dependent constant. We attribute the distinction between low- and high-Tc cuprates to the fine-tuning of the p–d–p fluctuation of the Cu-localized hole (nloc) visiting the neighboring planar–oxygen atoms, which is the reason for the material-dependence embodied in the constant Oₛ.