Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session P40: Domain Walls
3:00 PM–6:00 PM,
Wednesday, March 17, 2021
Sponsoring Units: GMAG DMP
Chair: Alexey Kovalev, University of Nebraska - Lincoln
Abstract: P40.00003 : Anomalous Chiral Exchange Drag in Synthetic Antiferromagnets
3:24 PM–4:00 PM
(IBM Research - Almaden)
(IBM Research - Almaden)
We recently discovered a new form of drag, “Chiral Exchange Drag”, that involves the exchange of angular momentum between two current-driven magnetic domain walls (DWs) from synthetic antiferromagnets . Previously we identified a powerful new torque, exchange coupling torque, in synthetic antiferromagnets that can move composite DWs very efficiently . I will present our new findings that the composite DWs motions are correlated and determined by the strength of the exchange drag between component DWs. For example, when the drag is below a threshold value, the DWs move together at a constant intermediate velocity with a steady leakage of angular momentum from the faster to the slower wall. On the other hand, I will show that when the drag exceeds a threshold value, an entirely different dynamic can take place in which the faster DW’s magnetization oscillates synchronously with a precessional motion of the slower DW’s magnetization, and angular momentum is continuously transferred between them: “Chiral Exchange Drag Anomaly”. In this talk, I will discuss a new method for delivering spin angular momentum remotely to magnetic entities showing analogues with massive Dirac fermions.
 B. N. Narozhny, and A. Levchenko, “Coulomb drag”, Rev. Mod. Phys. 88, 025003 (2016).
 S.-H. Yang, C. Garg, and S. S. P. Parkin, “Chiral Exchange Drag and Chirality Oscillations in Synthetic Antiferromagnets”, Nat. Phys. 15, 543 (2019).
 S.-H. Yang, K.-S. Ryu, and S. S. P. Parkin, “Domain-wall velocities of up to 750 m s− 1 driven by exchange-coupling torque in synthetic antiferromagnets”, Nat. Nano. 10, 221 (2015).
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