Spin-transfer torques for domain wall motion in antiferromagnetically coupled ferrimagnets

Antiferromagnetic materials offer ultrafast spin dynamics and could be used to build devices that are orders of magnitude faster than those based on ferromagnetic materials. Spin-transfer torque is key to the electrical control of spins and has been demonstrated in ferromagnetic spintronics. However, experimental exploration of spin-transfer torque in antiferromagnets remains limited, despite a number of theoretical studies. Here, we report an experimental examination of the effects of spintransfer torque on the motion of domain walls in antiferromagnetically coupled ferrimagnets. Using a ferrimagnetic gadolinium-iron-cobalt (GdFeCo) alloy in which Gd and FeCo moments are coupled antiferromagnetically, we find that non-adiabatic spin-transfer torque acts like a staggered magnetic field, providing efficient control of the domain walls. We also show that the non-adiabaticity parameter of the spin-transfer torque is significantly larger than the Gilbert damping parameter, in contrast to the case of non-adiabatic spin-transfer torque in ferromagnets.