HIGH-ENERGY NEUTRON-SCATTERING FROM HEAVY-FERMION SYSTEMS CE(IN1-XSNX)(3) AND CE(PT1-XRHX)(2)

We report neutron-scattering measurements on the heavy-Fermion systems Ce(In1-xSnx)(3) and Ce(Ptt-xRhx)(2). For x = a, the pure compounds Ce In3 and CePt2 order antiferromagnetically at 10.2 and 1.7 K, respectiv ely. Above these temperatures, in the paramagnetic phase, they show a quasi-elastic central 'peak' as well as a crystal-field excitation Gam ma(7) --> Gamma(8). As x increases the crystal-field excitation become s 'quenched' in both systems and the ground-state (F-2(5/2)) response degenerates into a single broad Lorentzian hump centered on a characte ristic energy which increases progressively to a value of similar to 3 5 meV for CeSn3 and as high as similar to 115 meV for CeRh2. In the se ries of compounds Ce(In1-xSnx)(3) the spin-orbit excitation F-2(5/2) - -> F-2(7/2) is found to shift progressively to higher energies with in creasing x. The increase with x above the free-ion value of similar to 273 meV is at a rate roughly twice the characteristic energy of the g round manifold. This implies that the characteristic energy of the F-2 (7/2) state is roughly twice that for the F-2(5/2) state. Similar enha ncements of the spin-orbit excitations in the system Ce(Pt1-xRhx)(2) a re expected.