Physical properties of the uranium ternary compoundsU3Bi4M3(M

Abstract

We report the properties of two new isostructural compounds, U 3 Bi 4 Ni 3 and U 3 Bi 4 Rh 3 . The first of these compounds is non-metallic, and the second is a nearly ferromagnetic metal, both as anticipated from their electron count relative to other U-based members of the larger '3-4-3' family. For U 3 Bi 4 Rh 3 , a logarithmic increase of C/T below 3 K, a resistivity proportional to T 4/3 , and the recovery of Fermi-liquid behavior in both properties with applied fields greater than 3T, suggest that U 3 Bi 4 Rh 3 may be a new example of a material displaying ferromagnetic quantum criticality.2

Hybridization-driven gap inU3Bi4Ni3: ABBaek1, Curro2, Klimczuk3 et al. 2009Phys. Rev. BSelf Cite326453View full textAdd to dashboardCite

“…21 Furthermore, the high quality of the Arrhenius fit rules out the possibility of an impurity band near the chemical potential. Photoemission results have revealed a gap in the density of states of 840 K, 15 roughly four times the gap measured by NMR. The origin of this difference is not clear, but may be related to spin versus charge excitations.…”

“…We note that this gap value is smaller than the value reported in ref. 15 but still larger than the gap values of most Ce-based Kondo insulators. 4 This difference between the 4f and 5f gap values may indicate the better hybridization between U 5f electrons and conduction electrons from Bi 6p and/or Ni 3d bands in U 3 Bi 4 Ni 3 .…”

“…The nuclear spin-lattice relaxation rate T −1 This result reveals the gapping of excited quasiparticles at low temperature, in agreement with resistivity measurements that show this material to be non-metallic, and specific heat measurements that reveal a vanishing Sommerfeld coefficient. 15 We would not expect these behaviors to arise from only depopulation of an excited crystal field level, such as found in U 3 Sb 4 Ni 3 . 21 Furthermore, the high quality of the Arrhenius fit rules out the possibility of an impurity band near the chemical potential.…”

“…To date, there are reports of Kondo insulating behavior in U 3 Sb 4 X 3 (X=Ni,Pt,Pd) and U 2 Ru 2 Sn. 10,11,12,13,14 The recently discovered uranium ternary compound U 3 Bi 4 Ni 3 is another potential candidate 15 that might be considered as the uranium counterpart of the well-known Kondo insulator Ce 3 Bi 4 Pt 3 . These compounds are not only isostructural, but also isoelectronic assuming the valance state of U is > 3+ but < 4+.…”

“…Each Bi atom has three U (and Ni) nearest neighbors that form an equilateral triangle on a plane perpendicular to its axis of symmetry. 15 A fully gapped ground state was inferred by specific heat and photoemission measurements, 15 in which spe-cific heat showed a Sommerfeld coefficient γ 0 ∼ 0 and the photoemission measurements revealed an electronic gap of 840 K. However, because Th 3 Bi 4 Ni 3 , which is nonmagnetic with Th 4+ , is also an insulator, these initial studies were unable to establish the origin of the gapped state in U 3 Bi 4 Ni 3 .…”