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Quantum Theory of Materials seminar, PGI-1/IAS-1

Prof. Johan Mentink

Image potential state from van der Waals density functional

begin
31 Oct 2018 11:30
venue
PGI Lecture Hall

Radboud University, Nijmegen, Netherlands

Abstract:

In 1915, Einstein and de Haas and Barnett demonstrated that changing the magnetization of a magnetic material results in mechanical rotation, and vice versa. At the microscopic level, this effect governs the transfer between electron spin and orbital angular momentum, and lattice degrees of freedom, understanding which is key for molecular magnets, nano-magneto-mechanics, spintronics, and ultrafast magnetism. Until now, the timescales of electron-to-lattice angular momentum transfer remain unclear, since modelling this process on a microscopic level requires addition of an infinite amount of quantum angular momenta. Recently we demonstrated that this problem can be solved by reformulating it in terms of the recently discovered angulon quasiparticles, which results in a rotationally invariant quantum many-body theory in which we can directly keep track of the angular momentum of the spin, orbital and phonon degrees of freedom. Importantly, the quasiparticle approach allows us to take non-perturbative into account and we demonstrate that they are crucial for the description of high frequency effects even if the electron–phonon coupling is weak. In particular, we find that already in the linear response regime angular momentum transfer can take place on femtosecond time scales.

Contact

Prof. Dr. Yuriy Mokrousov
Phone: +49 2461 61-4434
email: y.mokrousov@fz-juelich.de

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