Evidence for a High-Temperature Short-Range-Magnetic-Order Transition in MnO(001)

We report the observation of spin-polarized photoelectron diffraction for antiferromagnetic MnO(001). Data at kinetic energies near 100 eV for the spin-split Mn 3s multiplet show abrupt changes in the S5 intensity ratio at a temperature of 530±20 K that is 4.5 times the Néel temperature. An additional temperature-dependent study done at higher electron kinetic energies, along with azimuthal diffraction measurements, support the conclusion that this abrupt change is due to a new type of high-temperature short-range-magnetic-order transition. © 1989 The American Physical Society.