ELECTRON-SPIN-RESONANCE OF ER3+ IN YBIPT

We report low-temperature electron spin resonance (ESR) measurements i n YBiPt, doped with 0.1% Er substituting for Y. The results show that Er3+ is located at a cubic lattice site and has a Gamma(8)((3)) as gro und state and an overall crystal-field splitting of similar to 85(20) K. From the ESR spectra we inferred the existence of lattice distortio ns at the rare-earth site. These results may help in understanding the heavy-fermion system YbBiPt, which has the same structure as YBiPt.