Magnetic properties of RMn 6Sn 6 (R = Sc, Y, Gd−Tm, Lu) compounds with HfFe 6Ge 6 type structure

Abstract

Ternary stannides RMn 6Sn 6 (R = Sc, Y, Gd−Tm, Lu) have been synthesized from the elements. All the compounds are isotypic and crystallize in the HfFe 6Ge 6 type structure (filled derivative of CoSn-B35). Their magnetic behaviours were studied in the temperature range 4.2 K < T < 900 K. All these compounds order ferrimagnetically (Gd−Ho) or antiferromagnetically (Sc, Y, Er, Tm, Lu), up to rather high temperatures (333 K < T < 435 K). With R = Gd−Ho, both R and Mn sublattices order simultaneously above the room temperature while Er and Tm sublattices order only at 75 and 58 K respectively. RMn 6Sn 6 compounds with R = Tb−Ho exhibit a second magnetic transition below the Curie point, related to a reorientation of the easy axis magnetization, from the basal plane to the c axis. Some of these compounds (Tb−Er) exhibit large coercive fields (up to 11 kOe for TbMn 6Sn 6 at 4.2 K) related to uniaxial anisotropy.