Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Transport: Quantum Dots, Quantum Wires, Point Contacts I (TT jointly with O)
O 4.12: Vortrag
Montag, 31. März 2014, 12:30–12:45, BEY 81
Accumulation of spin anisotropy in a nanoparticle in the mesoscopic Stoner regime — •Philipp Stegmann1, Björn Sothmann2, and Jürgen König1 — 1Theoretische Physik, Universität Duisburg-Essen and CENIDE, 47048 Duisburg, Germany — 2Départment de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland
We theoretically discuss the accumulation of spin-quadrupole moment [1, 2] in an isotropic system giving rise to a large spin anisotropy although the spin-dipole moment remains strongly suppressed. Our system is a nanoparticle weakly tunnel coupled to two ferromagnetic leads. For such system, it has been demonstrated that the spin fluctuations give rise to enhanced shot noise [3]. Here, large positive spin-quadrupole moments are generated by abruptly switching off the bias voltage for parallel leads‘ polarizations. Moreover, applying an oscillating bias voltage results in large negative spin-quadrupole moments for parallel or antiparallel polarizations.
[1] B. Sothmann, and J. König, Phys. Rev. B 82, 245319 (2010).
[2] M. M. E. Baumgärtel, M. Hell, S. Das, and M. R. Wegewijs, Phys. Rev. Lett 107, 087202 (2011).
[3] B. Sothmann, J. König, and Y. Gefen, Phys. Rev. Lett. 108, 166603 (2012).