Eur. Phys. J. B 46, 289-299 (2005)
https://doi.org/10.1140/epjb/e2005-00227-y

Cotunneling through a quantum dot coupled to ferromagnetic leads with noncollinear magnetizations

¹ Department of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland
² Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznań, Poland

Corresponding author: ^a barnas@main.amu.edu.pl

Received: 9 December 2004
Revised: 2 April 2005
Published online: 26 July 2005

Abstract

Spin-dependent electronic transport through a quantum dot has been analyzed theoretically in the cotunneling regime by means of the second-order perturbation theory. The system is described by the impurity Anderson Hamiltonian with arbitrary Coulomb correlation parameter U. It is assumed that the dot level is intrinsically spin-split due to an effective molecular field exerted by a magnetic substrate. The dot is coupled to two ferromagnetic leads whose magnetic moments are noncollinear. The angular dependence of electric current, tunnel magnetoresistance, and differential conductance are presented and discussed. The evolution of a cotunneling gap with the angle between magnetic moments and with the splitting of the dot level is also demonstrated.