Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: INNOMAG e.V. Diploma-/Master Prize 2018

MA 15.3: Hauptvortrag

Montag, 12. März 2018, 17:35–17:55, H 0112

Unified description of high frequency magnetodynamics, and a new way of measuring the magnon contribution to the specific heat. — •Benjamin Zingsem^1,2, Michael Winklhofer³, Sabrina Masur⁴, Paul Wendtland¹, Ruslan Salikov¹, Florian M. Römer¹, Ralf Meckenstock¹, and Michael Farle¹ — ¹University Duisburg-Essen, 47057 Duisburg, Germany — ²ERC und PGI, Fz Jülich GmbH, 52425 Jülich, Germany — ³University of Oldenburg, 26129 Oldenburg, Germany — ⁴University of Cambridge, Cambridge CB3 0HE, UK

We present a general analytic solution of the ferromagnetic high frequency susceptibility tensor, as well as a new method of measuring the magnon contribution to the heat capacity in ferromagnetic systems, predicted by this solution. This linearized function can be directly applied to ferromagnetic systems with any magnetic energy landscape, any static applied fields and any sufficiently small dynamic fields. It unifies a multitude of approaches know throughout literature and naturally describes the entire reciprocal space for magnons in one simple function. In addition, this approach predicts a new type of metastable eigenmode which can be excited in conventional ferromagnetic resonance experiments, by sweeping the field in an unconventional way. These predicted modes where measured and the deduced behavior of the heat capacity is presented. Furthermore, by including the chiral Dzyaloshinskii-Moriya interaction, this formalism yields a possibility to determine the chiral energy density for small chiral coupling, which was previously inaccessible.