A 119Sn Mössabuer study of the magnetic to nonmagnetic transition in U(In 1-x > Sn x) 3

Abstract

The temperature and concentration dependence of the 119Sn Mössbauer spectrum has been measured for U(In 1- x Sn x ) 3. UIn 3 has an antiferromagnetic transition at 91.5 K determined using both Mössbauer and specific heat measurements, and USn 3 is a highly enhanced paramagnet. As Sn is substituted for In in UIn 3, the Néel temperature T N (as determined using the temperature dependence of the magnetic susceptibility) is depressed and appears to go to zero between x = 0.4 and x = 0.5. However, the magnetic hyperfine field determined by Mössbauer spectroscopy persists to higher Sn concentration and appears to go to zero in the vicinity of x = 0.6. The difference in magnetic-nonmagnetic boundary is attributed to the presence of short-range order as the system approaches the magnetic instability. Short-range correlation in the vicinity of x = 0.6 appear to be responsible for the apparent heavy-fermion behavior previously reported for this system. In addition, the results of the 119Sn Mössbauer studies for U(In, Sn) 3 are inconsistent with the magnetic structures previously proposed to explain neutron diffraction studies and a new magnetic structure is proposed which is consistent with both the neutron and Mössbauer studies.