Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 60: Magnetic Materials: Applications and Multielement Bulk Materials
MA 60.8: Vortrag
Freitag, 24. März 2017, 11:15–11:30, HSZ 101
Universal distribution of magnetic anisotropy of impurities in ordered and disordered nanograins — •Attila Szilva1, Peter Balla2,3, Olle Eriksson1, Gergely Zarand4, and Laszlo Szunyogh2,5 — 1Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75120 Uppsala, Sweden — 2Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki ut 8, H-1111 Budapest, Hungary — 3Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary — 4BME-MTA Exotic Quantum Phases *Lendulet* Group, Institute of Physics, Budapest University of Technology and Economics, H-1521 Budapest, Hungary — 5MTA-BME Condensed Matter Research Group, Budapest University of Technology and Economics, Budafoki u *t 8, H-1111 Budapest, Hungary
We examine the distribution of the magnetic anisotropy experienced by a magnetic impurity embedded in a metallic nanograin. Confinement of the electrons induces a magnetic anisotropy that is large, and can be characterized by five real parameters, coupling to the quadrupolar moments of the spin. For disordered grains they are randomly distributed and, for stronger disorder, their distribution is found to be characterized by random matrix theory. The probability of having small magnetic anisotropies is suppressed below a characteristic scale, leading to anomalies in the specific heat and the susceptibility at temperatures and produces distinct structures in the magnetic excitation spectrum of the clusters that should be possible to detect experimentally.