Study of the Mn–Mn exchange interactions in single crystals of RMn6Sn6 compounds with R = Sc, Y and Lu

In order to investigate the behaviour of the magnetic anisotropy and the Mn–Mn exchange interaction in RMn6Sn6 (R = rare earth) compounds, magnetic studies have been carried out on single crystals of RMn6Sn6 compounds in which R is one of the non-magnetic elements Sc, Y and Lu. The temperature dependence of the magnetization of these compounds has been measured with the field applied parallel and perpendicular to the crystallographic c-direction. Magnetic isotherms of the three compounds were measured at 4.2 K in magnetic fields up to 50 T, applied parallel and perpendicular to the c-direction, sufficiently high to reach the forced ferromagnetic state and to detect multiple field-induced transitions. For LuMn6Sn6, magnetic isotherms were measured also at a higher temperature of 150 K. From our results we may conclude that the magnetic anisotropy as well as the antiferromagnetic coupling strength increases in the sequence of ScMn6Sn6, YMn6Sn6 and LuMn6Sn6.