We present the results of electronic transport, magnetic susceptibility, and thermodynamic measurements on single crystals of the cubic compound Ce3Bi4Pt3. The susceptibility displays a broak peak centered at Tmax = 80K, which in Ce compounds is usually indicative of mixed valence and moderately heavy-electron behavior. Both the electronic transport properties and the low-temperature specific heat indicate that Ce3Bi4Pt4 is nonmetallic with a transport energy gap of roughly 35 K. We argue that this temperature is close to that scale over which coherence should develop in a periodic metallic system with Tmax = 80K. Resistivities typical of a Kondo-impurity system are realized when the compound is alloyed with moderate amounts of lanthanum. Further, lanthanum substitution increases the low-temperature specific heat to a value consistent with the single-ion energy scale determined from the magnetic susceptibility. © 1991.

We have synthesized the series of compounds RMIn5 and R2MIn8 in single crystal form, where R=Sm or Gd and M=Rh or Ir. These materials form in tetragonal derivatives of the Cu3Au structure RIn3. Measurements of magnetic susceptibility, electrical resistivity, and low-temperature heat capacity are reported. These compounds order antiferromagnetically at low temperature (TN < 45 K) and their low-temperature magnetic properties remain nearly unaltered compared to their SmIn3 and GdIn3 cubic relatives. The present data are compared to the magnetic properties of the isostructural (Ce, Nd) (Rh, Ir)In5 and (Ce, Nd)2(Rh, Ir)In8 compounds, and the validity of de Gennes scaling as a function of rare earth in a given structure is discussed. © 2001 The American Physical Society.

We present an analysis of transport data from Ce3Bi4Pt3 to deteermine the energy gap temperature dependence Eg(T). Eg(T) is a decreasing function of temperature. This result is consistent with the gap being a product of many-body correlations in which Eg(T) is scaled by the Kondo energy scale TK. © 1994.

The magnetoresistance (MR) of the narrow-gap Kondo insulator Ce3Bi4Pt3 and its non-magnetic analog La3Bi4Pt3 have been measured in magnetic fields to 10 T and in the temperature range 2-300 K. Ce3Bi4Pt3 exhibits a large negative MR component below 7 K. At higher temperatures this negative component progressively decreases and a positive contribution becomes evident. Above 75 K the MR is positive at all fields and saturates to a value of a few percent. The non-magnetic analog La3Bi4Pt3 exhibits the same positive magnetoresistance present in Ce3Bi4Pt3 as well as a conventional positive H2 term at low temperatures. We discuss potential mechanisms for both the common positive effect and the large negative MR present in Ce3Bi4Pt3. © 1993.

Doping studies are presented on three materials exhibiting hybridization gaps: Ce3Bi4Pt3, U3Sb4Pt3 and CeRhSb. In the case of trivalent La, Y, or Lu substituting for Ce or U, there is a suppression of the low temperature gap and an increase in the electronic specific heat, γ. In the case of tetravalent Th substitutions for U there is no change in γ and in the case of tetravalent Zr substitution for Ce in CeRhSb, there is an enhanced semiconductor-like behavior in the electrical resistance. These results are discussed in the light of a simple model of hybridization gapped systems. © 1992.

We present resistivity (T), susceptibility (T), and specific heat C(T) data for Ce3Bi4Pt3. The susceptibility exhibits a broad maximum centered near 80 K, typical of a somewhat-heavy-electron compound; were the material metallic, a linear coefficient of specific heat =75 mJ/mol Ce K2 would be expected. However, the compound is InotR metallic, as indicated by its resistivity which rises to large values at low temperatures and exhibits activated behavior with an activation energy /kB=35 K. By analogy to SmB6 and YbB12, this energy gap arises from 4f-electron conduction-electron hybridization. Due to the gap, electronic excitations are suppressed at low temperatures and the specific heat is smaller than in nonmagnetic La3Bi4Pt3. Alloying with lanthanum ((Ce1-xLax)3Bi4Pt3) decreases the resistivity and increases the specific heat towards the value expected for the metallic case; i.e., for moderate alloying (x=0.07) the behavior is that of a moderately disordered heavy-electron metal. We argue that lattice periodicity is an essential requirement for the formation of the hybridization gap. © 1990 The American Physical Society.

The anisotropic electrical resistivity and thermoelectric power S have been determined on single crystals of La2CuO4 in which the hole doping has been varied by controlled anneals. An enormous decrease and hysteresis in both and S occur at the Néel temperature TN for small, suggesting strong coupling between magnetic order and transport. Possible origins of these transport anomalies are discussed. © 1989 The American Physical Society.

Basic thermodynamic and transport properties of Ce3Bi4Pt3 are reviewed. Although the susceptibility displays a canonical mixed valence temperature dependence, the electrical resistance, thermoelectric power and specific heat are those associated with a small gap semiconductor in which the gap is due to hybridization of the renormalized f and conduction electrons. In addition to this, a surprising correlation between the magnetic susceptibility and the thermal expansion as well as a simple theoretical framework within which hybridization-gapped systems can be viewed are presented. © 1992.

We have used high pulsed magnetic fields to 50 T to observe de Haas - van Alphen oscillations in the tetragonal antiferromagnet CeRhIn5, which has an enhanced value of the electronic specific heat coefficient γ≥420 mJ/mol K2. For T

We report resistivity, magnetic, thermodynamic, and neutron-diffraction data for the heavy-fermion compound Ce5Sn3. These data indicate an antiferromagnetic phase transition at TN=17.5 K, but at lower temperatures the linear coefficient of specific heat (T)=C(T)/T rises to 1.6 J/f.u. mol K2, characteristic of a moderately-heavy-fermion compound. Only a small amount of entropy is liberated by the phase transition (R ln2), whereas most of the entropy [(34)R ln2] is liberated by heavy-fermion processes. This implies a small ordered moment. Further, neutron diffraction implies a rather complicated magnetic order. We discuss two alternatives: (a) that ordering occurs on the Ce site of higher symmetry, while heavy-fermion behavior occurs on the lower-symmetry Ce site; and (b) that itinerant-fermion antiferromagnetism occurs. Due to the overall low site symmetries, crystal-field effects are strong; in particular, the susceptibility is highly anisotropic (by a factor of at least 20 at low temperatures) and enhanced by the presence of strong ferromagnetic correlations in the heavy-fermion state. © 1991 The American Physical Society.