Induced-moment magnetic form factor of the heavy-fermion superconductors UPt3, UBe/sub 13/, and CeCu2Si2

Polarized neutron scattering techniques have been used to study the spatial distribution and temperature dependence of the magnetization induced in single crystals of UPt3, UBe/sub 13/, and CeCu2 Si2 by an externally applied magnetic field. We find that (a) the induced magnetization in the normal low-temperature state is predominantly of f-electronic character and that (b) the generalized electronic susceptibility chi(Q,0) (where Q is a reciprocal-lattice vector), obtained by measurements with H<H/sub c/2, is temperature independent between 4.2 K and approximately 0.1 K. This result implies either that the superconductivity in these compounds is unconventional or that there is significant spin-oribt scattering by impurities in the samples. This latter possibility notwithstanding, the experimental results impose severe restrictions on the possible superconducting states of these systems