Magnetism and structural chemistry of ternary silicides: (RE, Th, U)Pt 2Si 2 (RE = rare earth)

Abstract

Ternary silicides (RE, U, Th)Pt 2Si 2 have been prepared from the elements. All the compounds (RE= Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and U, Th) were found to be isotypic and crystallize with the primitive tetragonal CePt 2Si 2-type structure closely related to the CaBe 2Ge 2-type. The magnetic properties of these alloys were studied in the temperature range 1.5 K < T < 1100 K and in fields up to 1.3 T revealing a typical Van Vleck paramagnetism of free RE 3+-ions for temperatures T > 200 K. A nonmagnetic ground state is reflected from the magnetic susceptibility data of CePt 2Si 2, which are interpreted in terms of interconfiguration fluctuations (ICF). The magnetic results of SmPt 2Si 2 ( μ eff = 0.7 BM) compare well with the ideal Van Vleck behavior of Sm 3+ ions with a J = 5 2 ground state and a low-lying excited first level J = 7 2 . At temperatures below 40 K antiferromagnetic ordering is found for (Gd, Tb, U)Pt 2Si 2; whereas in case of (Dy, Ho, Er, Tm)Pt 2Si 2 the onset of ferromagnetism is indicated below 4 K. None of the samples exhibited a superconducting transition above 1.8 K.