SN-119 MOSSBAUER STUDY OF THE CEPTSN KONDO COMPOUND

We have measured Sn-119 Mossbauer spectra of the CePtSn and (Ce0.9La0. 1)NiSn compounds in the range from 1.5 to 293 K. In CePtSn, the spectr a observed above 8 K are well explained by an electric quadrupole inte raction. The spectral shape changes below 8 K due to the presence of a magnetic hyperfine field produced by the ordering of the Ce magnetic moments. We have analyzed these spectra assuming an incommensurate mag netic structure. The temperature dependence of the magnetic hyperfine field matches with an S = 1/2 mean field curve with a step at 5 K. In (Ce0.9La0.1)NiSn, no magnetic order exists down to 1.5 K.