Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 16: Spin Dynamics: Magnetic relaxation and Gilbert Damping
MA 16.3: Vortrag
Montag, 20. März 2017, 18:00–18:15, HSZ 401
Thermal emergence of laser induced spin dynamics for a Ni4 cluster — •Stefan Sold1, Wolfgang Hübner1,3, Bhaskar Kamble2, Georgios Lefkidis1, and Jamal Berakdar3 — 1University of Kaiserslautern and Research Center OPTIMAS, Kaiserslautern, Germany — 2Asia Pacific Center for Theoretical Physics, Pohang, Korea — 3Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
Using ab initio quantum chemistry we study the interplay of thermally-induced and laser-induced dynamics on the highly correlated magnetic Ni4 cluster. We find that due to this interplay new cooperative dynamics emerges, which is a result of the combination of the quantum coherences introduced to the system by the laser pulse and the electronic relaxation due to the bath: A bath temperature of 10<T<300 can help induce a spin flip, in cases the laser alone cannot.
Technically we propagate the density matrix of the system within the Markovian approximation, where the Lindblad superoperator describes the coupling to the bath [1]. By isolating the various electronic and spin relaxation channels we identify two different time regimes, both for the spins and for the charges [2], which we further analyze. We thus derive and discuss all phenomenological relaxation constants. Our quantum-thermodynamics findings on this prototypic system pave the way toward possible molecular spin-caloritronic applications.
[1] G. Schaller and T. Brandes, Phys. Rev. A 78, 022106 (2008)
[2] G. P. Zhang, W. Hübner, G. Lefkidis, Y. Bai, and T. F. George, Nature Phys. 5, 499 (2009)