Spin-charge-entangled Kondo effect induced by a side-coupled Majorana zero mode
Phys. Rev. B 112, 085123 – Published 13 August, 2025
DOI: https://doi.org/10.1103/kmpz-3ytk
Abstract
We investigate Kondo physics in a quantum dot side coupled to a Majorana zero mode, where the Majorana coupling induces both spin and charge fluctuations that determine low-energy behavior. Using a wave-function-based Schrieffer-Wolff transformation combined with numerical renormalization group calculations, we discover an spin-charge-entangled Kondo state, in which conduction electrons screen the spin-charge-entangled degrees of freedom of the Majorana-quantum dot subsystem. We show that the parity degeneracy of this state gives rise to spin-resolved Andreev-normal boundary conditions, resulting in non-Fermi-liquid behavior. Density matrix renormalization group simulations directly resolve a hallmark of these boundary conditions—a subleading even-odd effect in the screening cloud. Our framework bridges strongly correlated and topological phenomena, and naturally extends to parafermions and Kondo systems.