Modulated non-collinear magnetic structure of (Co0.9757Fe0.03)4Nb2O9 as revealed by Mössbauer spectroscopy

In this work, we present detailed 57Fe Mössbauer spectroscopy investigations of (Co0.9757Fe0.03)4Nb2O9 compound to study its possible magnetic structure. We have shown that the previously reported magnetic structures cannot satisfactorily describe our low temperature Mössbauer 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 Mössbauer 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. •Mössbauer spectroscopy probe of magnetic structures of magnetoelectric materials.•We report modulated non-collinear magnetic structure for (Co0.9757Fe0.03)4Nb2O9.•DFT calculation of the EFG tensor for the determination of magnetic structure.