ALLOYING-INDUCED TRANSITION FROM LOCAL-MOMENT TO ITINERANT HEAVY FERMION MAGNETISM IN CE(CU1-XNIX)2GE2

A monotonous increase of the Kondo temperature in Ce(Cu1-xNix)2Ge2 from 7 (x = 0) to 30 K (x = 1) is accompanied by drastic changes of ground state properties: for x≤0.2, a modulated magnetic structure (q01 = (0.28, 0.28, 0.54)) involving Kondo-reduced local Ce moments (μs = 0.74μB Ce for x = 0) forms below TN1(x). TN1 = 4. 1 K for CeCu2Ge2 is strongly depressed upon increasing x. At x ≲ 0.2, a different modulation develops below TN2(x) which becomes maximum (≃4 K) for x = 0.5. Since this is characterized by a very small value of q02 (=(0, 0, 0.13) at x = 0.5) and a gradually decreasing ordered moment (reaching μs ≲ 0.2μB/Ce for x ≥0.65), we ascribe it to "heavy fermion band magnetism". For 0.02≤x≤0.3, the two modulations seem to be superposed at sufficiently low temperatures. A non-magnetic heavy fermion ground state exists for x > 0.75. © 1990.