Polarized Magnetic Wire Induced by Tunneling Through a Magnetic Impurity

TL;DR

This paper calculates the conductance of a magnetic impurity wire coupled to Luttinger liquid leads, revealing how resonance conditions, temperature, and external fields influence spin-dependent conductance behavior.

Contribution

It introduces a zero mode method to analyze conductance in magnetic impurity wires with Luttinger liquid leads, highlighting spin asymmetry effects under external tuning.

Findings

Conductance scales as (T/T_F)^{2(α-2)} at resonance

Off-resonance conductance scales as (T/T_F)^{2(α-1)}

External fields induce spin-dependent conductance asymmetry

Abstract

Using the zero mode method we compute the conductance of a wire consisting of a magnetic impurity coupled to two Luttinger liquid leads characterized by the Luttinger exponent $\alpha(\leq 1)$. We find for resonance conditions, in which the Fermi energy of the leads is close to a single particle energy of the impurity, the conductance as a function of temperature is $G \sim \frac{e^2}{h} (T/T_F)^{2(\alpha-2)}$, whereas for off-resonance conditions the conductance is $G \sim \frac{e^2}{h} (T/T_F)^{2(\alpha-1)}$. By applying a gate voltage and/or a magnetic field, one of the spin components can be in resonance while the other is off-resonance causing a strong asymmetry between the spin-up and spin-down conductances.