Heavy-Fermion and Semiconducting Properties of the Ternary Uranium Compounds U₃T₃Sn₄and U₃T₃Sb₄(T=Ni, Cu, Pd, Pt and Au)

Inelastic neutron scattering study of U3Pt3Sb4

“…This would be consistent with a low carrier density, suggested by the low value of the Sommerfeld coefficient 3' of the heat 14- capacity and the activated form of the electronic conductivity. The neutron data is supportive of the conclusion that UaPt3Sb4, like other UaT3Sb 4 compounds, is a band semi-conductor [5]. For the $4 point symmetry of the U site it can be shown [6] that there is only one second-order crystal field parameter B °, two independent fourth-order (B ° and a 4) and three sixth-order parameters (B~, B 4 and B64).…”

On the low-temperature thermal properties and low-energy Fermi excitations in CeNiSn

“…Newly found ternary compounds include Ce and U elements from the beginning of the 4f and 5f rows which usually form metallic Kondo-type or mixed valence systems. Among these systems there are compounds Ce3Bi4Pt3, U3Sb4Pta with a well-defined and wide enough energy gap A ~ 50-200 K [2,3], and the equiatomic compounds CeNiSn I-4, 5] and CeRhSb 1-6] where the energy gap (or quasigap) was estimated as A < 10 K. Its existence in CeNiSn was established by studying the thermal, magnetic, transport and elastic properties. (see [1][2][3][4][5][6][7] for a review of recent experimental results).…”

Doping and pressure study of U3Sb4Pt3

“…The lack of ~/ enhancement with tetravalent doping is a feature of this system that must be accounted for in any attempt to model these systems theoretically and to (late may be the most important clue as to the origin of the gap in these materials. It is worth noting that there is an isostructural system in which both the uranium and thorium members have been examined: U3Sb4Ni3 and Th3Sb4Ni3 [6]. The reported gaps for the uranium and thorium members of this family are 0.20 and 0.07 eV respectively.…”

“…The U3Sb4Pta system is isostructural with CeaBi4Pt3 and has a gap of roughly 200 K. This system has been reported by Takabatake et al [6,7] and Takegahara et al [8] in its pure form as part of a larger study of the UaSb4T 3 (T---Ni, Cu, Pd, Pt, Au) systems, but a detailed investigation of the stability of the gap with respect to substitutions and pressure was not made. As will be shown, the effect of substitutions and pressure on the properties of U3Sb4Pt3 are similar to those found in the cerium analogue, but because the uranium system supports a wider variety of dopants, we are able to extend our knowledge of these gapped systems.…”