Evolution of crystalline electric field effects, superconductivity, and heavy-fermion behavior in the specific heat of Pr(Os1−xRux)4Sb12

N. A. Frederick; T. A. Sayles; M. B. Maple

doi:10.1103/PhysRevB.71.064508

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Evolution of crystalline electric field effects, superconductivity, and heavy-fermion behavior in the specific heat of Pr(Os1−xRux)4Sb12

N. A. Frederick, T. A. Sayles, M. B. Maple

DOI 10.1103/PhysRevB.71.064508 · Physical Review B

T1

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Abstract

Specific heat C(T) measurements were made on single crystals of the superconducting filled skutterudite series Pr(Os1−xRux)4Sb12 down to 0.6K. Crystalline electric field fits in the normal state produced parameters which were in agreement with previous measurements. Bulk superconductivity was observed for all values of the Ru concentration x with transition temperatures consistent with previous experiments, confirming a minimum in Tc at x=0.6. The C(T) data below Tc appear to be more consistent with power-law behavior for x=0 (PrOs4Sb12), and with exponential behavior for 0.05⩽x⩽0.2. An enhanced electronic specific heat coefficient γ was observed for x⩽0.4, further supporting x≃0.6 as a critical concentration where the physical properties abruptly change. Significant enhancement of ΔC∕Tc above the weak-coupling value was observed only for x=0 and 0.05.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
PrOs4Sb12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.85	Pressure not reported	unknown
PrRu4Sb12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.1	Pressure not reported	unknown
Pr(Os1-xRux)4Sb12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.75	Pressure not reported	unknown
PrOs4Sb12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.77	Pressure not reported	midpoint
Pr(Os0.95Ru0.05)4Sb12 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.63	Pressure not reported	midpoint