Spin dynamics and a nearly continuous magnetic phase transition in an entropy-stabilized oxide antiferromagnet

Studying magnetism in entropy-stabilized oxides (ESOs) is an exciting new research avenue following the recent discovery of antiferromagnetic order in (Mg${}_0.2$Co${}_0.2$Ni${}_0.2$Cu${}_0.2$Zn${}_0.2$)O (MgO-ESO). Muon spin relaxation and neutron scattering experiments reveal a continuous transition that occurs across a broad distribution of antiferromagnetic ordering temperatures throughout the MgO-ESO sample. The ground state exhibits a magnon gap and significant quasielastic neutron scattering, suggesting unusual intrinsic magnetic fluctuations. These results resolve several open questions about magnetic order in MgO-ESO and pave the way for future investigations of magnetic ESOs.