Elastic properties of the non-Fermi-liquid metalCeRu4Sb12and dense Kondo semiconductorCeOs4Sb12

Abstract

We have investigated elastic properties of the Ce-based filled skutterudite antimonides CeRu 4 Sb 12 and CeOs 4 Sb 12 by means of ultrasonic measurements. CeRu 4 Sb 12 shows a slight increase around 130 K in the temperature dependence of the elastic constants C 11 , ͑C 11 − C 12 ͒ / 2, and C 44 . No apparent lattice softening toward low temperature expected by a quadrupolar response of the 4f-electronic ground state of the Ce ion was observed at low temperatures. On the other hand, CeOs 4 Sb 12 shows a pronounced lattice softening toward low temperature in the longitudinal C 11 as a function of temperature below about 15 K, while a slight lattice softening was observed in the transverse C 44 below about 1.5 K, in contrast to no softening in CeRu 4 Sb 12 at low temperatures. Furthermore, CeOs 4 Sb 12 shows a steep drop around a phase-transition temperature of T s = 0.9 K in both C 11 and C 44 . The lattice softening observed in C 11 below about 15 K cannot be explained reasonably only by the crystalline electric-field ͑CEF͒ effect. Instead, it is most likely to be responsible for a coupling between elastic strain and a relevant renormalized quasiparticle band with a small energy gap in the vicinity of the Fermi level. The elastic properties and the 4f ground state of Ce ions in CeRu 4 Sb 12 and CeOs 4 Sb 12 are discussed in terms of the CEF effect and the band structure in the vicinity of Fermi level.

Rattling in Clathrate Compounds of ROs4Sb12and R3Pd20Ge6

“…On the other hand, the result obtained by Nakanishi shows a slight increase around 30 K, however, no apparent frequency dependence was found so far. 21 These results probably lead to the absence of rattling in CeOs 4 Sb 12 though the work is still continuing and support the idea that the contribution of conduction electrons is essential for the development of rattling through electron-phonon interaction. Figure 2 displays the temperature dependence of the relative change in elastic constants of the pure transverse C T = (C 11 − C 12 )/2 in (a) and C 44 in (b) of one other clathrate R 3 Pd 20 Ge 6 .…”

Microscopic study of antiferromagnetic ground state and possible high-field ordered state inCeOs4Sb12using muon spin rotation and relaxation

“…The AFQ ordering seems incompatible with the elastic constant in H ʈ ͓001͔, which shows no clear anomaly at T ‫ء‬ in high magnetic fields. 21 Meanwhile, a recent angleresolved specific-heat study revealed that the specific-heat anomaly at T ‫ء‬ is markedly suppressed in the case of H ʈ ͓001͔, in comparison with other field directions. 31 Therefore, elastic constant measurements in magnetic fields applied along the other field directions are necessary in order to discuss quadrupole interactions in high magnetic fields.…”

“…Moreover, specific-heat, resistivity, elastic constant, and the 1 / ͑T 1 T͒ anomalies at T ‫ء‬ become less distinctive with increasing magnetic field. 7,12,17,21 Thus, further investigations by means of microscopic probes are required to elucidate the nature of the unusual state at low temperatures.…”

Ab Initio Studies on Structural, Mechanical, Electronic, Magnetic, and Thermoelectric Transport Properties of CeCo4P12

“…Different combinations of Ce‐filled skutterudites have been reported in the literature. For example, electronic, optical, and transport properties of CeRu 4 Sb 12 have been studied by many researchers but their reported results are not consistent because it has been reported having semi‐metallic character, the metallic character with a pseudo‐gap of 0.09 eV, and semi‐conducting nature . Whereas CeRu 4 P 12 has been reported as a semiconductor with indirect band‐gap and CeFe 4 Sb 12 has been reported as semiconductor .…”