MAGNETIZATION OF CECU6 AT LOW-TEMPERATURES

The heavy-fermion system (HFS) CeCu6 shows no long-range magnetic order. However, antiferromagnetic (AF) correlations have been previously observed in ineleastic neutron scattering (INS). High-accuracy magnetization measurements on a single crystalline sample at very low temperatures are reported, which show a metamagnetic-like transition in magnetic fields B parallel-to c (orthorhombic notation). At T = 0.15 K, the susceptibility chi(c)(B) = dM(B)/dB exhibits a distinct maximum at B = 1.7 T. This maximum remains at the same field with increasing temperature, but becomes weaker until it finally disappears around T = 0.9 K. This new feature for CeCu6 coincides with the field where the AF-correlated excitations in the INS disappear. This supports the idea that a metamagnetic-like transition is a common feature of "nonmagnetic" HFS, even if - as in the case of CeCu6 - the AF-correlations are weak compared to local on-site fluctuations.