Observation of Pure Nuclear Diffraction from a Fe/Cr Antiferromagnetic Multilayer

The observation of nuclear resonant diffraction of synchrotron radiation from a exp 57 Fe/Cr multilayer is reported. The multilayer consists of 25 exp 57 Fe(17 A)/Cr(10 A) bilayers with the Cr layer thickness chosen so as to exhibit antiferromagnetic (AF) coupling of the exp 57 Fe layers. Because of the AF alignment of the layers, the magnetic periodicity of the multilayer is twice the electronic periodicity, resulting in a pure nuclear Bragg reflection that appears during nuclear resonant diffraction. The pure nuclear Bragg reflection presents a means of filtering synchrotron radiation to the level of 10 exp -8 eV at the nuclear resonance energy of 14.4 keV.