Magnetism of CePt2Sn2

CePt2Sn2 has the tetragonal P4/nmm structure. Polycrystalline (pcr) materia l possesses in addition a small monoclinic distortion and shows a magnetic transition below 1 K, while no such transition is seen in purely tetragonal single-crystalline (scr) samples. Our mu SR, specific heat and magnetizati on data are consistent with a spin-glass-like (sgl) state below 0.45 K in s cr and long-range order (lro) below 0.85 K in per samples. mu SR demonstrat es clearly that the Ce3+ spin ensemble remains dynamic down to lowest tempe ratures (0.02 K) in the sgl state. but reaches the usual quasi-static limit in the lro state. These results are discussed in terms of geometrical magn etic frustration. (C) 2000 Elsevier Science B.V. All rights reserved.