Europhys. Lett.
Volume 70, Number 6, June 2005
Page(s) 796 - 802
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 13 May 2005
Europhys. Lett., 70 (6), pp. 796-802 (2005)
DOI: 10.1209/epl/i2005-10043-1

Angular conductance resonances of quantum dots non-collinearly coupled to ferromagnetic leads

J. Fransson

Department of Materials Science and Engineering, Royal Institute of Technology (KTH) SE-100 44 Stockholm, Sweden and Physics Department, Uppsala University - Box 530, SE-751 21 Uppsala, Sweden and NORDITA - Blegdamsvej 17, DK-2100 Copenhagen, Denmark

received 22 February 2005; accepted in final form 22 April 2005
published online 13 May 2005

The zero-bias conductance of quantum dots coupled to ferromagnetic leads is investigated. In the strong-coupling regime, it is found that the conductance is a non-monotonic function of the angle between the magnetisation directions in the two contacts. This behaviour is an effect of the presence of the leads which induces an angle-dependent spin-split of the quantum dot states, and spin-flip transitions between the quantum dot states whenever the magnetisation directions of the leads are non-collinear, which enhances the current density at the chemical potential. In the weak-coupling regime, the system reverts to normal spin valve character.

72.25.Mk - Spin transport through interfaces.
73.63.Kv - Quantum dots.
73.23.Hk - Coulomb blockade; single-electron tunneling.

© EDP Sciences 2005