Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 78: Focus Session: Spinorbitronics - From Efficient Charge/Spin Conversion Based on Spin-Orbit Coupling to Chiral Magnetic Skyrmions I (joint session MA/TT)

TT 78.7: Talk

Thursday, March 15, 2018, 12:00–12:15, H 1012

Determination of the Dzyaloshinskii-Moriya interaction in epitaxial asymmetric trilayers — •Fernando Ajejas¹, Adrian Gudin¹, Ruben Guerrero¹, Diane Chaves², Viola Křižáková², Jan Vogel², Stefania Pizzini², Paolo Perna¹, and Julio Camarero¹ — ¹IMDEA Nanociencia, Campus Universidad Autónoma de Madrid, Spain — ²CNRS, Institut Néel, Université Grenoble Alpes, 38042 Grenoble, France

We will address the issue of domain wall velocity limitations in ultrathin magnetic films in symmetric and non-symmetric stacks. The DW wall speed is in general limited by the breakdown. This limitation is overcome in asymmetric trilayer systems in which Co is deposited on a heavy metal: in this case the Dzyaloshinskii-Moriya interaction (DMI) favours chiral Néel walls that are more stable against precession. It has been shown that in asymmetric thin layer systems the domain wall speed saturates above the Walker field, which is in general not the case for symmetric samples. Using magneto-optical Kerr magnetometry and microscopy, we measured domain wall velocities driven by magnetic field pulses in Pt/Co/Pt and Pt/Co/M (M=Al, Cu, Ir,) Typical Co thicknesses is 0.6 nm. The main result is that the saturation velocity of the DWs in the Pt/Co/M trilayers is strongly dependent on the nature of the top interface. We attribute this variation to the different contribution of the Co/M interfaces to the total DMI strength. The largest saturation velocities (typically 300m/s) are obtained for the samples covered by Al, Cu, or an oxyde, while much smaller velocities (typicaly 100m/s) are obtained for Ir or Ta top layers.