Keynote Talk 

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Stanislas Rohart: "Current induced dynamics of skyrmions in ultrathin ferromagnetic films"

Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Orsay, France

Skyrmions, a magnetic texture characterized by its unique topological charge, have attracted recently a concerted effort to study how they could be controlled and moved in ferromagnetic films, and open a new route for spintronics and information storage technologies [1]. Stabilization, nucleation and motion are the three challenges toward such an achievement [2]. In this talk, we show how skyrmions can be stabilized in ultrathin magnetic films. The films are in contact with high spin-orbit interaction, which induce a chiral magnetic exchange, the Dzyaloshinskii-Moriya interaction, that promotes magnetic non collinearity and the particular topology required for skyrmions. The magnetic textures are observed with magnetic force microscopy. In samples patterned in nanotracks, electrical current is injected and moves the skyrmions with velocities of few tens of meter per seconds for current densities of few 10¹¹A/m² [3,4]. Additionally, the skyrmions display an intrinsic deflection, related to the topology. In recent results, we show that, in synthetic antiferromagnetic films (two ferromagnetic layers coupled antiferromagnetically through a spacer), the deflection can be compensated thanks to the formation of a bound state of two skyrmions with opposite topological numbers [5].

[1]  A. Fert, V. Cros and J. Sampaio Nature Nano. 8 (2013) 152

[2]  J. Sampaio et al. Nature Nano 8 (2013) 184422

[3] A. Hrabec et al. Nature Com. 8 (2017) 15765

[4] S. Mallick et al. under submission

[5] S. Panigrahy et al. in preparation