Uranium moment collapse in magnetically diluted US

Muon spin rotation/relaxation (mu SR) measurements were carried out on sing le crystalline specimens of UxLa1-xS with x = 1, 0.8, 0.55, 0.4, 0.15 and 0 in the temperature range between 300 and 0.1 K. The limiting compounds US and LaS are ferromagnetic and diamagnetic, respectively. In the pseudo-bina ry system a collapse of the U magnetic moment was observed in bulk magnetic and neutron diffraction studies at x < 0.6. There neutrons no longer were able to detect magnetic order. Our mu SR data verify the moment collapse be low x = 0.6 but show that it leads to weak (between 0.3 and 0.05 mu(B)), bu t not vanishing U moments. Furthermore, all componds except the diamagnetic LaS exhibit a magnetic transition with the transition temperature decreasi ng linearly with diminishing U content. (C) 1999 Published by Elsevier Scie nce B.V. All rights reserved.