UFe4P12 and CeFe4P12: Nonmetallic isotypes of superconducting LaFe4P12

Abstract

The new compound UFe4P12, which was found to be isostructural to superconducting LaFe4P12 and have a lattice constant of 7.7729 Å, is a semiconductor and shows ferromagnetic order below 3.15 K. CeFe4P12 is also a semiconductor, and its magnetic susceptibility is unusually small in comparison to LaFe4P12. The semiconducting behaviors of both UFe4P12 and CeFe4P12 seem anomalous and may arise from strong f-electron hybridization.

Fermi-surface topologies and low-temperature phases of the filled skutterudite compoundsCeOs4Sb12andNdOs4Sb12

“…Filled skutterudite compounds, with the formula MT 4 X 12 , where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1][2][3][4][5][6][7][8][9] . Amongst these, the three compounds CeOs 4 Sb 12 , PrOs 4 Sb 12 , and NdOs 4 Sb 12 , formed by employing Periodic- Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal 1,2 or perhaps Kondo insulator (M = Ce) [10] via a 1.85 K unconventional (quadrupolarfluctuation mediated 11 ) superconductor (M = Pr) [8] to a 1 K ferromagnet (FM; M = Nd) [12].…”

Band Gap Stability in Kondo Insulators

“…Among the strongly correlated f-electron systems are stoichiometric compounds with small-gap semiconductor properties, which might be expected to be metallic, judging from the properties of their f-series analogous. The discovery of several Sm-, Tm-, Yb-, and U-based Kondo insulators, e.g., SmS [1], SmB 6 [2], TmSe [3], YbB 12 [4], UFe4Ρ12 [5], UNiSn [6], and FeSi [7], has renewed and enhanced the interest in this subject.…”

Collapse of the Gd3+ ESR fine structure throughout the coherent temperature of the Gd-doped Kondo Semiconductor CeFeVenegas1, Garcia2, García3 et al. 2016Phys. Rev. B80100View full textAdd to dashboardCite

“…The low-T transport properties of these materials are similar to conventional semiconductors, but in contrast to what is expected from simple thermal activation, the gap seems to disappear at a temperature * T , which is low relative to the gap size, indicating strong collective behavior [20,21]. Concerning 4 12 CeFe P , its semiconducting properties at low-T were considered anomalous when compared to other isostructural members of this class of compounds, most of which are metallic and magnetic [22].…”

“…Surprisingly, this temperature scale is about the same as the temperature * 150 T ≈ K, which marks the loss of coherence of heavy-fermion behavior, obtained from resistance experiments [20].…”