Magnetic properties of terbium B12 icosahedral boron-rich compounds

Static magnetic susceptibility of the new B-12 icosahedral higher boride compound TbB50 was measured and a large change in behavior around 17 K was observed, indicating the existence of an antiferromagnetic-like transition. At high fields a metamagnetic transition was observed to occur and the magnetic phase diagram was determined. This is the first report of a magnetic transition being observed in the higher boride compounds. An interesting feature of this behavior is that it is in contrast to the typical Curie-Weiss behavior of the more terbium rich compound TbB25 and also the more boron rich compound TbB66 which were also synthesized and measured in this work. This is considered to be an aspect of the unique structure of the REB50 (RE=rare-earth) compounds recently discovered.