Theory of Magnetic Mössbauer Diffraction Measurement

Abstract

The theory of Mössbauer $\gamma$-ray diffraction by magnetically ordered crystals containing Mössbauer nuclei is developed in the Born approximation. It is shown that for crystals whose magnetic structure induces an ordering of magnetic fields at Mössbauer nuclei, the diffraction patterns exhibit magnetic Bragg maxima. The positions of these maxima do not coincide generally with the positions of Rayleigh maxima. The polarization of radiation scattered at Bragg angles contains information about the orientation of the magnetic fields at the Mössbauer nuclei relative to the crystallographic directions. The expressions for the polarization and coherent scattering cross section are given in the case of large nuclear Zeeman splitting for a purely nuclear scattering. Diffraction by antiferromagnetic crystals is examined in detail. The possibility of studying magnetic ordering in crystals by means of Mössbauer diffraction is discussed.