  Spintronics, which is the basis of a low-power, beyond-CMOS technology for
computational and memory devices, remains up to now entirely based on critical
materials such as Co, heavy metals and rare-earths. Here, we show that Mn4N, a
rare-earth free ferrimagnet made of abundant elements, is an exciting candidate
for the development of sustainable spintronics devices. Mn4N thin films grown
epitaxially on SrTiO3 substrates possess remarkable properties, such as a
perpendicular magnetisation, a very high extraordinary Hall angle (2%) and
smooth domain walls, at the millimeter scale. Moreover, domain walls can be
moved at record speeds by spin polarised currents, in absence of spin-orbit
torques. This can be explained by the large efficiency of the adiabatic spin
transfer torque, due to the conjunction of a reduced magnetisation and a large
spin polarisation. Finally, we show that the application of gate voltages
through the SrTiO3 substrates allows modulating the Mn4N coercive field with a
large efficiency.
