Magnetism and heavy fermions in YbRhSn and YbPtSn

Abstract

Isostructural YbRhSn and YbPtSn were studied by specific heat, electrical resistivity, and magnetoresistance. Both compounds order antiferromagnetically below 2 and 3.5 K, respectively. Above 4 K, they display a number of remarkable similarities including Kondo-like resistivity and large negative magnetoresistance. Scaling analysis of this magnetoresistance shows that it is due to the suppression of Kondo scattering in YbRhSn but has a ferromagnetic spin fluctuation character in YbPtSn. The heavy fermion state was confirmed in YbRhSn by low temperature specific heat measurements yielding γ of about 1200 mJ/K2 mol. γ for YbPtSn is of order 100 mJ/K2 mol only.