Transport properties and thermopower of the spinful Sachdev-Ye-Kitaev dot

Abstract

We study the electric and thermoelectric transport through a spinful complex Sachdev-Ye-Kitaev (SYK) quantum dot coupled to metallic leads, forming a N-SYK-N junction, by the Keldysh field theory approach. Unlike traditional equilibrium approaches, our formulation treats the system as an open, interacting quantum conductor under non-equilibrium conditions, without resorting to the replica trick. Starting from the exact Keldysh-Dyson equations, we derive analytical results for the tunneling and zero-temperature limits and perform a numerical analysis in the linear-response regime. We characterize the dependence of conductance, thermoelectric coefficient, and Seebeck effect on the particle-hole asymmetry parameter and coupling strength to the leads. Our results reveal distinctive non-Fermi liquid signatures of the SYK model in transport properties and identify coupling regimes where thermoelectric effects are enhanced, suggesting experimentally accessible fingerprints of SYK physics in mesoscopic systems.

Figures (7)

• Figure 1: Linear conductance $G$ in units of the conductance quantum $G_0=2e^2/h$ as a function of the particle-hole asymmetry parameter $\theta$ at fixed temperature ($\beta=10$) for different values of the coupling $\Gamma$.
• Figure 2: Thermoelectric coefficient $L$ in units of $ek_B/h$ as a function of the particle-hole asymmetry parameter $\theta$ at fixed temperature ($\beta=10$) for different values of the coupling $\Gamma$.
• Figure 3: Thermopower $S=L/G$ in units of $k_B/e$ as a function of the particle-hole asymmetry parameter $\theta$ at fixed temperature ($\beta=10$) for different values of the coupling $\Gamma$.
• Figure 4: Linear conductance $G$ in units of the conductance quantum $G_0=2e^2/h$ as a function of the coupling $\Gamma$ at fixed temperature ($\beta=10$) for different values of the particle-hole asymmetry parameter $\theta$.
• Figure 5: Thermoelectric coefficient $L$ in units of $ek_B/h$ as a function of the coupling $\Gamma$ at fixed temperature ($\beta=10$) for different values of the particle-hole asymmetry parameter $\theta$.