Switching Reciprocity On and Off in a Magneto-Optical X-Ray Scattering   Experiment Using Nuclear Resonance of 57Fe Foils
  Reciprocity is when the scattering amplitude of wave propagation satisfies a symmetry property, connecting a scattering process with an appropriate reversed one. We report on an experiment using nuclear resonance scattering of synchrotron radiation, which demonstrates that magneto-optical materials do not necessarily violate reciprocity. The setting enables to switch easily between reciprocity and its violation. In the latter case, the exhibited reciprocity violation is orders of magnitude larger than achieved by previous wave scattering experiments. 
L. De\'ak, L. Botty\'an, T. F\"ul\"op, G. Kert\'esz, D. L. Nagy, R.   R\"uffer, H. Spiering, F. Tanczik\'o, and G. Vank\'o
nucl-ex nucl-th