Concentrational commensurate-incommensurate magnetic phase transition in Y1 − xTbxMn6Sn6

The magnetic state of Y1 − x Tb x Mn6Sn6 (with x ≤ 0.25) alloy is studied at different temperatures and magnetic fields by neutron diffraction. The alloy with x c = 0.22 exhibits an incommensurate-to-commensurate structure phase transition. The transition is accompanied by a decrease in the unit-cell volume. The weak dependence of the intensity of satellites on the x concentration and the monotonic displacement of their angular positions with increasing x allow us to conclude that the antiferromagnet → ferrimagnet transition occurs through the uniform magnetic state. The incommensurate phase in YMn6Sn6 exhibits four satellites, which are observed in the low-angle range of X-ray diffraction pattern and demonstrate different behavior with changing temperature. At 293 K, the antiferromagnet → ferromagnet transition in the Y1 −x Tb x Mn6Sn6 compound can be induced by applied magnetic field, in particular, the field μ0 H = 0.3 T induces the transition in Tb0.15Y0.85Mn6Sn6.