Influence of Fe doping on the Yb valence state and the magnetic structures in HoFe6Sn6-type YbMn6-yFeySn6 alloys (y ≤ 1.00)

Abstract

Abstract We determine the magnetic structures of HoFe6Sn6-type (Immm) YbMn6-yFeySn6 alloys (y = 0.25, 0.50, 0.75 and 1.00) from powder neutron diffraction experiments. The valence state and local magnetism of Yb are investigated using X-ray Near Edge Spectroscopy (XANES) and X-ray Magnetic Circular Dichroism (XMCD) at the Yb L3 edge. The mean Yb valence decreases upon Fe doping (from υ ~ 2.66 down to υ ~ 2.46) and there is no 4\xa0f Yb magnetism throughout the series. The Fe for Mnsubstitution leads to change in the spins arrangement of the 3d sublattice by reinforcing antiferromagnetic exchange interactions without significant change in T = Mn/Fe moment magnitude (m ~ 2.35 µB). The ground state of the alloy with y = 0.25 is ferromagnetic whilst Fe richer alloys are helimagnets with wave-vector k = 0, qy, 0. The turn-angle increase upon Fe doping manifests by a mitigation of the Yb L3 dichroic effect, solely due to hybridization between its 5d states and the self-polarized 3d states of T.