Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 34: Spin Dynamics and Transport: Magnonics
MA 34.13: Vortrag
Mittwoch, 22. März 2017, 12:45–13:00, HSZ 04
Femtosecond quantum spin dynamics induced by femto-nanomagnons in Heisenberg antiferromagnets — •Olena Gomonay1, Davide Bossini2, Johan Metnik3, and Jairo Sinova1 — 1Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany — 2University of Tokyo, Japan — 3Radboud University Nijmegen, Nijmegen, The Netherlands
The major interest of spintronics has recently directed to antiferromagnets which could allow high density storage in a memory device and high frequencies of data processing entering the THz regime.
The use of all-optical schemes opens a way towards the ultrafast manipulation of an antiferromagnets, which up to now was restricted to low-energy magnons at the center of the Brillouin zone. Here we focus on the impulsively generated coherent magnons with the wavevector near the edges of the Brillouin zone -- femto-nanomagnons.
We investigate the macrospin dynamics induced by femto-nanomagnons and propose a simple quantum mechanical description of the two-magnon excitation mechanism, based on a light-induced modification of the exchange. We demonstrate that femto-nanomagnonics dynamical regime has purely quantum mechanical nature and that the dynamics is exclusively longitudinal. A complete description of the squeezed-states induced by the femto-nanomagnons is also reported. We also formulate an effective phenomenological theory of the femtosecond longitudinal spin dynamics. We believe that our results pave a way to manipulation and control of squeezed states in the magnetic systems.