Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 2: Magnetic Clusters
MA 2.4: Vortrag
Montag, 31. März 2014, 10:15–10:30, HSZ 401
Ab initio thermodynamics and heat nanoengines on the magnetic Ni2 dimer — •Wolfgang Hübner, Chuanding Dong, Debapriya Chaudhuri, and Georgios Lefkidis — Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany
We use the highly correlated excited electronic states of Ni2, calculated with the symmetry-adapted-cluster configuration-interaction method, to develop thermodynamic processes and build heat engines with molecular magnets. Identifying the work of a thermodynamic process with the energy shift of the electronic- and spin levels, and the heat exchange with their population change [1] we derive an isobaric process [2] and build a Diesel and an Otto nanoengine, as well as a novel engine for which a laser pulse substitutes for the hot bath.
The many internal degrees of freedom and the nonthermal effects allow crossings of adiabatic processes in a P−V diagram. We analyze the efficiency of the nanoengines and find a signifficant possible enhancement connected to the quantum nature, the spin and the heat capacity of Ni2, as well as to the zero-field splitting of the triplet states. These new concepts connect spin dynamics with quantum thermodynamics and suggest new ways of designing effective magnetic heat-engines.
(In collaboration with J. Berakdar and L. Chotorlishvili, Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Germany.)
[1] M. O. Scully, Phys. Rev. Lett. 88, 050602 (2002)
[2] C. D. Dong, G. Lefkidis and W. Hübner, J. Supercond. Nov. Magn. 26, 1589 (2013)