title: Terahertz-Driven Nonlinear Spin Response of Antiferromagnetic Nickel Oxide.
abstract: Terahertz magnetic fields with amplitudes of up to 0.4 Tesla drive magnon resonances in nickel oxide while the induced dynamics is recorded by femtosecond magneto-optical probing. We observe distinct spin-mediated optical nonlinearities, including oscillations at the second harmonic of the 1 THz magnon mode. The latter originate from coherent dynamics of the longitudinal component of the antiferromagnetic order parameter, which are probed by magneto-optical effects of second order in the spin deflection. These observations allow us to dynamically disentangle electronic from lattice-related contributions to magnetic linear birefringence and dichroism-information so far only accessible by ultrafast THz spin control. The nonlinearities discussed here foreshadow physics that will become essential in future subcycle spin switching.
authors.affiliation: Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Baierl
authors.affiliation: Radboud University, Institute of Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: Mentink
authors.affiliation: Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hohenleutner
authors.affiliation: Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Braun
authors.affiliation: Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: T-M
authors.initials: TM
authors.lastname: Do
authors.affiliation: Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Lange
authors.affiliation: Department of Physics, University of Konstanz and TOPTICA Photonics AG, Lochhamer Schlag 19, 82166 Gräfelfing, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Sell
authors.affiliation: Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Fiebig
authors.affiliation: Institute of Physics, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Woltersdorf
authors.affiliation: Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kampfrath
authors.affiliation: Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Huber