Magnetic to nonmagnetic behavior in U(Sn,Pb)3

Publisher Website
Google Scholar
Abstract
The magnetic to nonmagnetic transition in actinide alloys and intermetallic compounds is attributable to the delocalization of the 5f electrons due to an increase in the f‐f overlap and/or f‐spd hybridization. USn3 is paramagnetic at all temperatures and appears to be very near the border between magnetic and nonmagnetic behavior. In contrast, UPb3 has an antiferromagnetic transition at 31 K and the 5f electrons appear to be highly localized. Both of these systems have sufficiently large U‐U separations to expect that f‐spd hybridization is the major contributing factor to the delocalization of the 5f electrons. The room temperature lattice constant and the temperature dependence of magnetic susceptibility and electrical resistivity have been measured for the U(Sn1−xPbx)3 system to examine the salient features associated with the onset of long range magnetic behavior in this system. The room temperature lattice constant follows Vegard’s Law from USn3 to UPb3 and thus indicates no significant change in the degree of localization of the 5f electrons. Upon substitution of Sn for Pb in UPb3 (i.e., decreasing x), the Neel temperature TN initially increases to 38 K at x=0.7 then decreases and appears to go to zero between x=0.0 and x=0.1. Also, the spin fluctuation temperature Tsf for the USn3 rich alloys (i.e., xx. The pressure dependence of Tsf for USn3 (dTsf/dP=l.08 K/kbar) and TN for UPb3 (dTN/dP=0.26 K/kbar) has been measured. The x dependence of Tsf and TN along with the pressure dependence of these quantities is discussed in terms of the expected trend in f‐spd hybridization.