Dresden 2017 – wissenschaftliches Programm
MA 23.3: Vortrag
Dienstag, 21. März 2017, 10:00–10:15, HSZ 403
Ultrafast excitation of coherent magnons by circularly and linearly polarized light pulses in antiferromagnetic NiO — •Christian Tzschaschel1, Ryugo Iida2, Tsutomu Shimura2, Hiroaki Ueda3, Stefan Günther1, Takuya Satoh2,4, and Manfred Fiebig1 — 1ETH Zürich, Switzerland — 2The University of Tokyo, Japan — 3Kyoto University, Japan — 4Kyushu University, Japan
NiO is rapidly gaining importance in the field of antiferromagnetic magnonics. In this talk, we clarify the mechanism of ultrafast optical magnon excitation in antiferromagnetic NiO. We employed time-resolved optical two-color pump-probe measurements to study the coherent non-thermal spin dynamics. By near-infrared pumping and probing along the optical axis, we avoid the detrimental influence of birefringence. Thus, we are able to determine the mechanism behind the ultrafast optical magnon generation with linearly and circularly polarized light. For this purpose, we employ a phenomenological theory under consideration of the crystallographic and magnetic point group symmetries. Based on this new approach, we are able to describe the dynamic magneto-optical properties of NiO and derive expressions for the optically induced magnetization via the inverse Faraday effect as well as the inverse Cotton-Mouton effect. Our experimental and theoretical results are in striking agreement. This not only allows us to discriminate between the two effects, but also to extract information about the antiferromagnetic domain distribution. Moreover, we find that magnon generation via the inverse Cotton-Mouton effect is more than 30 times more efficient in NiO than via the inverse Faraday effect.