Time: Wednesday, October 24th, 10:10
Speaker: Olena GOMONAY, Mainz
In the present work we focus on the high-frequency dynamics of Heisenberg antiferromagnet related with the impulsively generated coherent magnons with the wavevector near the edges of the Brillouin zone -- femto-nanomagnons. We present experimental and theoretical investigation of 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 can be explained in terms of two-magnon entangled states. Since the conventional decription of spin dynamics relies on classical torque equation of motions, which are not applicable in the present case, we fill this gap by formulating 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.