Precession-free domain wall dynamics in compensated ferrimagnets.

One fundamental obstacle to efficient ferromagnetic spintronics is magnetic precession, which intrinsically limits the dynamics of magnetic textures. It was recently shown that higher domain wall (DW) mobility (Caretta 2018; Hrabec 2018; Kim 2017; Siddiqui 2018; Yang 2015), lower topological deflection of skyrmions (Hirata 2019; Woo 2018), and lower critical currents (Bang 2016; Woo et al. 2018) could be obtained by using materials with multiple spin sub-lattices, such as antiferromagnets, ferrimagnets, or synthetic antiferromagnets. We study DWs driven by spin-orbit torque in a ferrimagnetic GdFeCo/Pt track, and we demonstrate that the DW precession fully vanishes with a record mobility at the temperature for which the net angular momentum is compensated (TAC). We use a new method based on transverse in-plane fields that reveals the internal structure of DWs and provides a robust and parameter-free measurement of TAC. Our results put in a clear light the mechanism of faster and more efficient dynamics in systems with a reduced net angular momentum and their promise for high-speed, low-power spintronics applications.