Antiferromagnetism in BaF$_{2}$/Fe$_{x}$Ni$_{1-x}$F$_{2}$ bilayers

A series of crystalline BaF$_{2}$/epitaxial (110) Fe$_{x}$Ni$_{1-x}$F$_{2}$ samples were deposited on MgF$_{2}$ (110) via molecular beam epitaxy. The Fe concentration x was determined from x-ray diffraction measurements of the [110] lattice parameter. The actual thickness of each layer and the roughness of each interface were determined by fitting x-ray reflectivity data. The antiferromagnetic ordering of samples with x = 0.04, 0.27, 0.40, 0.46, 0.50, and 0.85 were studied and compared with BaF$_{2}$/NiF$_{2}$ (x=0) and BaF$_{2}$/FeF$_{2}$ (x=1) bilayers, via standard magnetometry measurements. A significant enhancement of the N\'{e}el temperature in alloys and evidence of spontaneous magnetization along c-axis were found.