Unconventional magnetoresistance induced by sperimagnetism in GdFeCo

We investigate the magnetoresistance of ferrimagnetic GdFeCo across the magnetization compensation temperature ${T}_{\mathrm{M}}$. The magnetic field dependence of longitudinal resistivity (${\ensuremath{\rho}}_{\mathrm{xx}}$) shows opposite trends below and above ${T}_{\mathrm{M}}$, and the variation of ${\ensuremath{\rho}}_{\mathrm{xx}}$ with $B$ becomes more significant as the temperature decreases. The observed unconventional magnetoresistance is attributed to the sperimagnetism of GdFeCo. Further investigations on the transverse resistivity (${\ensuremath{\rho}}_{\mathrm{xy}}$) of GdFeCo unveils that, contrary to the recent reports that the transition metal dominates transport of rare-earth transition-metal ferrimagnets, the Gd contribution to magnetoresistance is comparable to the FeCo contribution, showing that the transport of GdFeCo is antiferromagnetic. Our results therefore show that ferrimagnets are a convenient platform for studying antiferromagnetic spin transport and also are potential materials that can enable antiferromagnetic spin devices.