Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 9: Magnetic domain walls
MA 9.12: Vortrag
Montag, 12. März 2018, 18:00–18:15, EB 202
Exchange coupling torque in antiferromagnetically coupled Co/Gd bi-layer system — •Robin Bläsing1,2, See-Hun Yang3, Tianping Ma1,2, Chirag Garg1,2,3, and Stuart S. P. Parkin1,2,3 — 1Max Planck Institute for Microstructure Physics, Halle , Germany — 2Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany — 3IBM Research Almaden, San Jose, USA
In antiferromagnetic and ferrimagnetic thin films the efficiency of current-induced domain wall motion (CIDWM) by spin Hall currents from a heavy metal underlayer like Pt can be dramatically raised compared to ferromagnetic systems. As soon as the total angular momentums of the magnetic sublattices are equal, the torque due to the Dzyaloshinskii Moriya interaction (DMI) tends to zero and the more efficient exchange coupling torque becomes the dominant driving force. We carried out CIDWM experiments in antiferromagnetically coupled Co/Gd systems at base temperatures between 125 K and 250 K. The change of the magnetization of Gd due to the change of temperature within this range allows to compensate the total magnetic angular momentum of the Gd and Co sublayers at a compensation temperature Tτ≈ 219 K which is slightly higher than the magnetic moment compensation temperature at TM = 210 K. Our data suggests the existence of DMI in Co arising at the Co/Gd interface which effective field is opposite to that of the DMI at the Pt/Co interface. Based on findings of our 1D model, we develop a novel method to measure heating effects in a two-material based magnetic bi-layer system and prove an efficiency boost due the exchange coupling torque at Tτ