Modulated non-collinear magnetic structure of ((Co0.97Fe0.03)-Fe-57)(4)Nb2O9 as revealed by Mossbauer spectroscopy

In this work, we present detailed Fe-57 Mossbauer spectroscopy investigations of ((Co0.97Fe0.03)-Fe-57)(4)Nb2O9 compound to study its possible magnetic structure. We have shown that the previously reported magnetic structures cannot satisfactorily describe our low temperature Mossbauer spectra. Therefore, in combination with theoretical calculations, we have proposed a modulated helicoidal magnetic structure that can be used to simulate the whole series of our low temperature Mossbauer spectra. Our results suggest that the combination of previously reported different magnetic structures are only approximations of the average magnetic structure from our modulated helicoidal model. We anticipate that the proposed modulated non-collinear magnetic structure might shed light on the understanding of the complex magnetoelectric effects observed in this system.