HEAVY FERMIONS - TYPICAL PHENOMENA AND RECENT DEVELOPMENTS

A survey is given of typical phenomena, new materials and recent developments in heavy-fermion physics. In particular, the following topics are addressed: (i) YbNiAl, a new heavy-fermion local-moment antiferromagnet (LMM) with Neel temperature T(N) = 3 K, (ii) ''non-Fermi-liquid'' behavior at the magnetic instability in two heavy-fermion systems with intact from sublattice, i.e. orthorhombic CePt(Si1-xGex) and tetragonal U(Cu4+xAl8-x), (iii) the low-temperature properties of the anisotropic ''Kondo insulator'' CeNiSn, and (iv) some of the most unusual observations made on ''low-carrier-density'' rare-earth systems like Sm3Te4 and Sm3Se4. While the ezotic symmetry-broken (superconducting and magnetic) ground states of heavy-fermion metals are discussed in several other contributions to this volume, we focus in the remainder of this paper on the relationship between LMM ordering and heavy-fermion superconductivity: Firstly, the LMM ordered compound CeCu2Ge2 (T(N) = 4.1 K) is addressed which was recently found to become a non-magnetic heavy-fermion superconductor under high hydrostatic pressure, p greater-than-or-equal-to 70 kbar (D. Jaccard et al., Phys. Lett. A 163,475 (1992)). Point-contact spectroscopy is used to investigate in more detail the high-pressure superconducting phase of CeCU2Ge2. Secondly, we summarize high-pressure results on UPd2Al3, the first compound to show homogeneous coexistence between LMM ordering and heavy-fermion superconductivity.