Neutron diffraction measurements were performed (on the same single crystals used in our STM experiments) at the BT-7 thermal triple axis spectrometer at the NIST Center for Neutron Research using a 14.7-meV energy and collimation: open - 25′ - sample - 25′ - 120′. The magnetic intensity at the (1,0,0.5) peak was compared to the nuclear intensity at the (1,0,1) peak, while the temperature dependence of the (1,1,0.5) peak was used to calculate an order parameter. An f2 magnetic form factor was assumed. The error bars correspond to uncertainty of 1 SD.