Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 4: Transport: Quantum Dots, Wires, Point Contacts 1 (jointly with HL and TT)
O 4.7: Talk
Monday, March 11, 2013, 11:15–11:30, H20
Spin dynamics in nanoparticles near Stoner instability — •Philipp Stegmann1, Björn Sothmann2, Jürgen König1, and Yuval Gefen3 — 1Theoretische Physik, Universität Duisburg-Essen and CENIDE, 47048 Duisburg, Germany — 2Départment de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland — 3Dept. of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
We analyse the spin dynamics of a nanoparticle close to the Stoner instability. The nanoparticle is weakly tunnel coupled to two ferromagnetic leads. By mapping to an effective Fokker-Planck description we identify two different types of dynamic behaviour (diffusion vs. drift), which are revealed by characteristic relaxation times and a Fano factor that oscillates as a function of an applied bias voltage. Finally, we propose biasing schemes to generate states with magnetic quadrupole moments that dominate over a negligible dipole moment.