Anomalous Low-Lying Thermal Excitations Deep Inside the Ferromagnetic State in Filled Skutterudite NdFe4As12

作者：Higashinaka Ryuji^*; Takeda Kenki; Namiki Takahiro; Aoki Yuji; Sato Hideyuki

来源：Journal of the Physical Society of Japan, 2013, 82(11): 114710.

DOI：10.7566/JPSJ.82.114710

• skutterudite
• caged structure
• Kondo effect
• itinerant ferromagnet

The low-temperature properties of NdFe4As12 single crystals grown by the As self-flux method under high pressure have been studied by magnetization, electrical resistivity, and specific heat measurements. We found that NdFe4As12 shows a ferromagnetic transition at T-c = 14.6 K. Moreover, we found additional anomalies, a shoulder in the resistivity and a Schottky-like peak in magnetic specific heat below T-c. It is rare that the corresponding peak of the specific heat is larger than the specific heat jump at T-c. From the crystal electric field analysis of Nd 4f electrons with a simple mean field approximation, we found that a model with a quasi-degenerate sextet (doublet and quartet) reproduces these anomalous features qualitatively, but quantitative differences, probably attributable to the contribution from Fe d electrons, still remain. We also found that the effective magnetic moment (4.43 mu(B)/f.u.) is larger than the Nd3+ free-ion value (3.67 mu(B)/ion), indicating the contribution of Fe itinerant magnetism.

• 出版日期2013-11