Combined 57Fe Mössbauer-NMR experiments using FeNi alloys

We present the experimental details of observing the influence of NMR transitions between sublevels of Zeeman split nuclear states on Mossbauer spectra of FeNi alloys. Magnetically soft FeNi foils were subjected to radio-frequency (rf) magnetic fields and 57 Fe Mossbauer spectra were recorded. Splitting of Mossbauer resonance lines was observed when the frequency of the external transverse rf magnetic field was close to the resonance frequency of either the ground or the excited state. We discuss the possible reasons why a well-resolved line splitting has not been previously observed in earlier works.