We measured the temperature dependence of the structural parameters and the occurrence of magnetism in UPdSn and UCuSn using neutron diffraction. The data were taken in an effort to understand the role of hybridization effects for the development of the uranium magnetic moment and the occurrence of long-range magnetic order in these two compounds. The shortest U-U distance provides a measure of delocalization due to direct 5f-5f overlap, while the U-Pd (or U-Cu, respectively) and U-Sn distances give a measure of the effects of 5f -ligand hybridization. Using Rietveld refinement of our neutron diffraction data, we determined the shortest interatomic distances for temperatures between 15 K and room temperature. The changes in the interatomic distances cause changes in the hybridization effects, which in turn leads to the formation of a magnetic ground state for both compounds.
Bibliographical noteFunding Information:
This work was supported by a grant from NSF (Grant No. DMR-0804032). The work at the Los Alamos Neutron Science Center was partly supported by the Basic Energy Sciences program of the U.S. Department of Energy.