Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: Focus Session: Skyrmionics: Future of Spintronics? (jointly with MA)

TT 15.5: Invited Talk

Monday, March 16, 2015, 17:15–17:45, H 0104

Racetrack Memory: Highly Efficient Current Induced Domain Wall Motion in Synthetic Antiferromagnetic Racetracks — •Stuart Parkin — Max Planck Institute for Microstructure Physics, Halle, Germany — IBM Research - Almaden, San Jose, California, USA

Memory-storage devices based on the current controlled motion of domain walls in magnetic racetracks promise performance and reliability beyond that of conventional magnetic disk drives and solid state storage devices. Racetracks that are formed from atomically thin, perpendicularly magnetized nano-wires, interfaced with adjacent metal layers with high spin-orbit coupling, give rise to domain walls possessing a chiral Néel structure. These domain walls can be moved very efficiently with current. However, high capacity racetrack memory requires closely-packed domain walls whose density is limited by dipolar coupling from their fringing magnetic fields. These fields can be eliminated using a spin-engineered synthetic antiferromagnetic (SAF) structure composed of two magnetic sub-layers, exchange-coupled via an ultrathin antiferromagnetic-coupling spacer layer. We show that nano-second long current pulses can move domain walls in SAF racetracks that have nearly no net magnetization. Surprisingly, we find that the domain walls can be moved even more efficiently and at much higher speeds of up to ∼ 750 m/sec compared to similar racetracks in which the sub-layers are coupled ferromagnetically. The origin of these giant current induced domain wall velocities is discussed.