title: Macrospin dynamics in antiferromagnets triggered by sub-20 femtosecond injection of nanomagnons.
abstract: The understanding of how the sub-nanoscale exchange interaction evolves in macroscale correlations and ordered phases of matter, such as magnetism and superconductivity, requires to bridging the quantum and classical worlds. This monumental challenge has so far only been achieved for systems close to their thermodynamical equilibrium. Here we follow in real time the ultrafast dynamics of the macroscale magnetic order parameter in the Heisenberg antiferromagnet KNiF3 triggered by the impulsive optical generation of spin excitations with the shortest possible nanometre wavelength and femtosecond period. Our magneto-optical pump-probe experiments also demonstrate the coherent manipulation of the phase and amplitude of these femtosecond nanomagnons, whose frequencies are defined by the exchange energy. These findings open up opportunities for fundamental research on the role of short-wavelength spin excitations in magnetism and strongly correlated materials; they also suggest that nanospintronics and nanomagnonics can employ coherently controllable spin waves with frequencies in the 20 THz domain.
authors: Institute for Molecules and Materials, Spectroscopy of Solids and Interfaces, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: D
authors: D
authors: Bossini
authors: Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.|Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.
authors: S
authors: S
authors: Dal Conte
authors: Institute for Molecules and Materials, Spectroscopy of Solids and Interfaces, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Y
authors: Y
authors: Hashimoto
authors: Institute for Molecules and Materials, Spectroscopy of Solids and Interfaces, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: A
authors: A
authors: Secchi
authors: Ioffe Physical-Technical Institute, Ferroics Physics Laboratory, Russian Academy of Sciences, St Petersburg 194021, Russia.
authors: R V
authors: RV
authors: Pisarev
authors: Institute for Molecules and Materials, Spectroscopy of Solids and Interfaces, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Th
authors: T
authors: Rasing
authors: Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.|Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.
authors: G
authors: G
authors: Cerullo
authors: Institute for Molecules and Materials, Spectroscopy of Solids and Interfaces, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: A V
authors: AV
authors: Kimel