TY - JOUR
T1 - Field-insensitive heavy fermion features and phase transition in the caged-structure quasi-skutterudite Sm3 Ru4 Ge13
AU - Nair, Harikrishnan S.
AU - K., Ramesh Kumar
AU - Britz, Douglas
AU - Ghosh, Sarit K.
AU - Reinke, Christian
AU - Strydom, André M.
N1 - Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/6/5
Y1 - 2016/6/5
N2 - The robust field-insensitive heavy fermion features in Sm3 Ru4 Ge13 and the magnetic phase transition at TN ≈ 5 K are studied using magnetization M(T), specific heat Cp(T), resistivity ρ(T) and thermal conductivity κT(T). The average crystal structure of Sm3 Ru4 Ge13 conforms to the cubic space group Pm3¯n however, signatures of subtle structural distortions are obtained from the x ray data. The magnetic susceptibility, χ(T), follows a modified Curie–Weiss law indicating the presence of crystal fields of Sm3+ and the significance of van Vleck terms. No sign of ferromagnetism is observed in M(H) of Sm3 Ru4 Ge13 which yields only 0.025 μB/f.u.-Sm at 2 K, 7 T. The Sommerfeld coefficient, γ≈ 220 mJ/mol-Sm K2, estimated from the analysis of low temperature specific heat suggests the formation of heavy quasi particles at low temperature. Though a lnT dependence of ρ(T) is observed till 60 K, the resistivity behavior is accounted for by assuming a two-band model for activated behavior of charge carriers. The field scans of resistivity, ρ(H), below TN display significant nonlinearity while those above the TN are more metal-like. Low values of thermal conductivity, κT(T), are observed in Sm3 Ru4 Ge13 however, displaying an anomaly at TN which signifies magnetoelastic coupling. A fairly high value of Seebeck coefficient, S ≈ 40 μV/K is observed at 300 K. We identify Sm3 Ru4 Ge13 as a low charge carrier density system with unusual field-insensitive heavy fermion features very similar to the filled skutterudites.
AB - The robust field-insensitive heavy fermion features in Sm3 Ru4 Ge13 and the magnetic phase transition at TN ≈ 5 K are studied using magnetization M(T), specific heat Cp(T), resistivity ρ(T) and thermal conductivity κT(T). The average crystal structure of Sm3 Ru4 Ge13 conforms to the cubic space group Pm3¯n however, signatures of subtle structural distortions are obtained from the x ray data. The magnetic susceptibility, χ(T), follows a modified Curie–Weiss law indicating the presence of crystal fields of Sm3+ and the significance of van Vleck terms. No sign of ferromagnetism is observed in M(H) of Sm3 Ru4 Ge13 which yields only 0.025 μB/f.u.-Sm at 2 K, 7 T. The Sommerfeld coefficient, γ≈ 220 mJ/mol-Sm K2, estimated from the analysis of low temperature specific heat suggests the formation of heavy quasi particles at low temperature. Though a lnT dependence of ρ(T) is observed till 60 K, the resistivity behavior is accounted for by assuming a two-band model for activated behavior of charge carriers. The field scans of resistivity, ρ(H), below TN display significant nonlinearity while those above the TN are more metal-like. Low values of thermal conductivity, κT(T), are observed in Sm3 Ru4 Ge13 however, displaying an anomaly at TN which signifies magnetoelastic coupling. A fairly high value of Seebeck coefficient, S ≈ 40 μV/K is observed at 300 K. We identify Sm3 Ru4 Ge13 as a low charge carrier density system with unusual field-insensitive heavy fermion features very similar to the filled skutterudites.
KW - Field-insensitive
KW - Heavy fermion
KW - Quasi-skutterudite
KW - Samarium
UR - http://www.scopus.com/inward/record.url?scp=85044267395&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2016.01.259
DO - 10.1016/j.jallcom.2016.01.259
M3 - Article
AN - SCOPUS:85044267395
SN - 0925-8388
VL - 669
SP - 254
EP - 261
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
ER -