Goldanskii-Karyagin effect and external magnetic field method as tools to measure anisotropy of the recoilless fraction in amorphous materials

Abstract

Diffraction of X-rays or neutrons can not be used to obtain details about the atomic vibrational anisotropy in the case of amorphous materials due to the lack of well-defined Bragg reflections. Mossbauer spectroscopy can yield some information in such cases, either via the Goldanskii-Karyagin effect or by applying a magnetic field, preferably along the beam axis. The latter method can be applied to the (preferably diamagnetic) samples exhibiting an electric quadrupole interaction (preferably non-axial) and the magnetic field should be chosen in such a way as to produce significant off-diagonal elements in the hyperfine hamiltonian. The external magnetic field method is capable of yielding much more information than the Goldanskii-Karyagin effect in most cases, provided sufficiently strong magnetic fields are available. Some examples of the129I Mossbauer spectra have been calculated to show the usefulness and sensitivity of the external magnetic field method.