Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 45: Spintronics (incl. Quantum Dynamics)
(Joint session of MA, HL and TT organized by MA)
TT 45.4: Vortrag
Mittwoch, 9. März 2016, 10:15–10:30, H32
Optically and thermally driven spin dynamics and quantum Otto cycles on Ni4 structures — •Stefan Sold1, Bhaskar Kamble2, Georgios Lefkidis1, and Wolfgang Hübner1 — 1Departement of physics, University of Kaiserslautern and Research Center OPTIMAS, Germany — 2Asia Pacific Center for Theoretical Physics, Pohang, Korea
We present two different kinds of combined optical and thermodynamic processes on the chain-like prototypical Ni4 cluster, described on the basis of high-level quantum chemistry. The one consists of incoherent spin relaxation and thermalization processes, the other one of a nano Otto engine.
First, we model various temperature profiles by coupling to one or two temperature baths. The system dynamics is mathematically described with the Lindblad superoperator [1]. We find that the inhomogeneous temperature profile, giving rise to non-equilibrium mixed states, induces non-uniform spin-density distribution (spin Seebeck effect on the nano scale).
Second, we propose a quantum Otto motor [2], which benefits from the spin degree of freedom and the energy discretization of the cluster, and may thus surpass the efficiency limit of classical Carnot cycles [3].
- [1] G. Schaller and T. Brandes, Phys. Rev. A 78, 022106 (2008)
- [2] W. Hübner, G. Lefkidis, C. D. Dong, D. Chaudhuri, L. Chotorlishvili, and J. Berakdar, Phys. Rev. B 90, 024401 (2014)
- [3] C. D. Dong, G. Lefkidis, and W. Hübner, Phys. Rev. B 88, 214421 (2013)