Zero-bias anomaly in cotunneling transport through quantum-dot spin valves

TL;DR

This paper predicts a novel zero-bias conductance anomaly in quantum-dot spin valves caused by cotunneling processes affecting spin accumulation, distinct from the Kondo effect, and modifiable by magnetic fields.

Contribution

It introduces a new zero-bias anomaly in cotunneling transport through quantum dots with ferromagnetic leads, highlighting its origin and magnetic field dependence.

Findings

The anomaly appears in Coulomb-blockade valleys with unpaired electrons.

It results from interplay between single- and double-barrier cotunneling.

Magnetic fields significantly modify the anomaly.

Abstract

We predict a new zero-bias anomaly in the differential conductance through a quantum dot coupled to two ferromagnetic leads with antiparallel magnetization. The anomaly differs in origin and properties from other anomalies in transport through quantum dots, such as the Kondo effect. It occurs in Coulomb-blockade valleys with an unpaired dot electron. It is a consequence of the interplay of single- and double-barrier cotunneling processes and their effect on the spin accumulation in the dot. The anomaly becomes significantly modified when a magnetic field is applied.