Specific Heat Study on Sm-based Filled Skutterudite Phosphides SmT4P12 (T=Fe, Ru and Os)

Sm-based filled skutterudite phosphides SmFe 4 P 12 , SmRu 4 P 12 and SmOs 4 P 12 synthesized at high temperatures and high pressures have been studied by specific heat measurements in magnetic fields. SmFe 4 P 12 shows an anomaly at 1.6 K attributed to a ferromagnetic transition. SmRu 4 P 12 shows a metal–insulator transition at 16 K. This transition consists of two successive transitions, which suggests orbital and antiferromagnetic orderings. SmOs 4 P 12 shows a sharp anomaly at 4.5 K due to an antiferromagnetic ordering. We discuss the characteristic behavior of those phase transitions and the crystalline electric field state in Sm T 4 P 12 ( T =Fe, Ru and Os). Interestingly, the magnetic entropy of SmFe 4 P 12 have only 0.16 R ln 2 below the ferromagnetic ordering temperature. This suggests a strong spin fluctuation effect. On the other hand, the variation of magnetic entropy in SmRu 4 P 12 and SmOs 4 P 12 reaches to nearly R ln 4 below the ordering temperature.

[1]  C. Sekine,et al.  Ferromagnetic heavy fermion behavior in filled skutterudite compound SmFe4P12 by 31P-NMR , 2004 .

[2]  C. Sekine,et al.  Elastic anomalies of polycrystalline SmRu4P12 associated with metal-insulator transition , 2004 .

[3]  N. Takeda.  Ferromagnetic heavy fermion compound SmFe4P12 , 2003 .

[4]  K. Miyoshi,et al.  NMR study of magnetic properties in SmRu4P12 , 2003 .

[5]  M. Yokoyama,et al.  Magnetic properties of Sm-based filled skutterudite phosphides , 2003 .

[6]  H. Harima,et al.  Fermi surface instability in Pr-based skutterudites , 2002 .

[7]  E. Bauer,et al.  Superconductivity and heavy fermion behavior in PrOs 4 Sb 12 , 2002 .

[8]  K. Abe,et al.  Exotic heavy-fermion state in the filled skutterudite PrFe 4 P 12 uncovered by the de Haas-van Alphen effect , 2000, cond-mat/0010003.

[9]  G. Kido,et al.  Metal–Insulator Transition of Filled Skutterudite Compound SmRu4P12 , 2002 .

[10]  H. Harima,et al.  Crystal Electric Fields for Cubic Point Groups , 2001 .

[11]  T. Goto,et al.  Magnetic properties of the filled skutterudite-type structure compounds GdRu 4 P 12 and TbRu 4 P 12 synthesized under high pressure , 2000 .

[12]  H. Sato,et al.  Unusual behaviors in the transport properties of REFe$_{4}$P$_{12}$ (RE: La, Ce, Pr, and Nd) , 2000, cond-mat/0010017.

[13]  M. Ishikawa,et al.  Superconducting and Magnetic Properties of Filled Skutterudite Compounds RERu4Sb12(RE=La,Ce,Pr,Nd and Eu). , 2000 .

[14]  T. Yagi,et al.  Superconductivity of LaRu4X12 (X = P, As and Sb) with skutterudite structure , 1999 .

[15]  C. Sekine,et al.  Micro-probed raman scattering study of ternary ruthenium phosphides with filled skutterudite-type structure , 1998 .

[16]  T. Yagi,et al.  Metal-Insulator Transition in PrRu{sub 4}P{sub 12} with Skutterudite Structure , 1997 .

[17]  T. Yagi,et al.  Superconductivity of filled skutterudites LaRu{sub 4}As{sub 12} and PrRu{sub 4}As{sub 12} , 1997 .

[18]  R. K. Williams,et al.  Filled Skutterudite Antimonides: A New Class of Thermoelectric Materials , 1996, Science.

[19]  T. Yagi,et al.  Electrical conductivity and superconductivity of metal phosphides with skutterudite-type structure prepared at high pressure , 1996 .

[20]  F. Steglich,et al.  Crystal-field effects and f-derived specific heats in heavy-fermion compounds , 1988 .

[21]  Maple,et al.  Pressure-dependent magnetism and electrical resistivity of UFe4P , 1987, Physical review. B, Condensed matter.

[22]  Maple,et al.  Low-temperature properties of rare-earth and actinide iron phosphide compounds MFe4P12 (M = La, Pr, Nd, and Th). , 1987, Physical review. B, Condensed matter.

[23]  Rasul,et al.  Specific heat of the degenerate Kondo model: Exact results in the presence of crystal fields. , 1987, Physical review. B, Condensed matter.

[24]  G. Meisner,et al.  UFe4P12 and CeFe4P12: Nonmetallic isotypes of superconducting LaFe4P12 , 1985 .

[25]  G. Meisner,et al.  The pressure dependence of the superconducting transition temperature of LaT4P12(T = Fe, Ru, Os) , 1985 .

[26]  K. Yosida,et al.  Comments on the Dense Kondo State , 1984 .

[27]  V. T. Rajan.  Magnetic Susceptibility and Specific Heat of the Coqblin-Schrieffer Model , 1983 .

[28]  G. Meisner.  Superconductivity and magnetic order in ternary rare earth transition metal phosphides , 1981 .

[29]  W. Jeitschko,et al.  LaFe4P12 with filled CoAs3‐type structure and isotypic lanthanoid–transition metal polyphosphides , 1977 .

[30]  J. Schrieffer,et al.  EXCHANGE INTERACTION IN ALLOYS WITH CERIUM IMPURITIES. , 1969 .