Theory and Experiment of Current Noise through Kondo Dot under Magnetic Fields

We present a comprehensive theoretical and experimental investigation of bias-voltage nonlinear current noise arising from the spin-1/2 Kondo effect in a carbon nanotube quantum dot at low temperatures, with a varying applied magnetic field. In the presence of a magnetic field, linear currents and linear current noise are found to be determined by two spin-dependent phase shifts. However, nonlinear currents and nonlinear noise not only stem from one-body correlations (phase shifts) and two-body correlations (Wilson ratio and renormalization factor), as treated in the Fermi liquid theory at zero magnetic fields but also from the Fermi-liquid correction induced by three-body correlations[1-3]. In our cryogenic experiments employing a carbon nanotube quantum dot with two aluminum electrodes, we observe nonlinear current noise. We elucidate the nature of the Fermi-liquid correction attributed to the three-body correlations. Furthermore, we explore the scaling universality of nonlinear current noise and the magnetic field response of the Fermi-liquid correction by comparing our experimental data with the analysis of the Fermi-liquid theory, employing numerical renormalization groups calculation and exact solutions.

[1] Christophe Mora, Cătălin Paşcu Moca, Jan von Delft, and Gergely Zaránd, PRB 92, 075120 (2015).

[2] Yoshimichi Teratani, Rui Sakano, and Akira Oguri, PRL 12, 216801 (2020).

[3] Tokuro Hata, Yoshimichi Teratani, Tomonori Arakawa, et al., Nat. Comm. 12, 3233 (2021).