Antiferromagnetic Ordering on CoO(001) Studied by Metastable Helium Beam   Diffraction
  Magnetic diffractive scattering of coherent metastable helium atomic beams from CoO(001) surfaces reveal the presence of an anomalous enhancement in the intensity of the half-order antiferromagnetic diffraction peak over the temperature range of 250-320K. Electronic cluster calculations based on Hartree-Fock states with configuration interactions, together with mean-field and Monte Carlo studies of this system suggest that this behavior is associated with low-lying surface spin excited states. 
P. Banerjee, X. Liu, M. Farzaneh, C.R. Willis, W. Franzen, M.   El-Batanouny and V. Staemmler