Dresden 2017 – wissenschaftliches Programm
MA 23.5: Vortrag
Dienstag, 21. März 2017, 10:30–10:45, HSZ 403
Picosecond time-evolution of Cu2OSeO3’s helimagnetic order parameter after photoexcitation studied by time-resolved spontaneous Raman spectroscopy — •Rolf B. Versteeg1, Jingyi Zhu1, Christoph Boguschewski1, Petra Becker2, and Paul H.M. van Loosdrecht1 — 1II. Physikalisches Institut, Universität zu Köln, Cologne, Germany — 2Abteilung Kristallographie, Institut für Geologie und Mineralogie, Cologne, Germany
Time-resolved Raman spectroscopy is a seldom used tool in the investigation of picosecond magnetization dynamics. This is mostly due to a combination of the low inelastic light scattering rate, and the restrictions on time-resolution, and needed spectral resolution. A successful realization of such an experiment would however lead to valuable insights into symmetry changes after optical perturbation, quasiparticle population statistics, and excitation energy changes on ultrafast timescales.
Here, we present the ultrafast dynamics of helimagnetic order in the chiral magnet Cu2OSeO3 studied by time-resolved picosecond spontaneous Raman spectroscopy. This material has attracted significant research interest due to the presence of a Skyrmion lattice phase. The ground state of this material consists of helimagnetically ordered S = 1 spin clusters, which are composed of 3-up-1-down Cu S = 1/2 spins. The magnetic excitations within the spin-cluster are Raman-active, and serve as a probe for helimagnetic order. We show that after photoexcitation the helimagnetic order "melts" through spin-lattice relaxation on typical timescales of ∼100 ps.