Crossover and coexistence of superconductivity and antiferromagnetism in the filled-skutterudite system Pr1−xEuxPt4Ge12

Abstract

The superconducting and normal-state properties of the filled-skutterudite system Pr1−xEuxPt4Ge12 were studied. Polycrystalline samples were investigated via x-ray diffraction, electrical resistivity, magnetic susceptibility, and specific heat measurements. Upon Eu substitution, we observed a crossover from superconducting to antiferromagnetic states with a region where both states coexist. In the superconducting region, the specific heat data exhibit a change of temperature dependence, suggesting an evolution from a nodal to a nodeless superconducting energy gap or a suppression of multiband superconductivity. This change is relatively slower than those reported for different substituent ions, suggesting paramagnetic impurities have a weaker pair breaking effect on unconventional superconductivity in PrPt4Ge12. In the normal state, an evolution from Fermi-liquid to non-Fermi-liquid behavior was observed, accompanied by the coexistence of superconductivity and antiferromagnetism, suggesting the underlying electronic structure is primarily responsible for the complex physical phenomena found in this system.

Short-range antiferromagnetic correlations in the superconducting state of filled skutterudite alloys Pr1−xEuxPt4Ge12

“…2(a) specific heat C − C ph data as a function of T obtained after subtracting the phonon contribution (obtained from the above fit) from the measured specific heat of the samples that display superconducting transition in heat capacity and resistivity measurements. A superconducting transition is clearly observed for Pr 1−x Eu x Pt 4 Ge 12 samples with x ≤ 0.3 in heat capacity measurements, whereas this phase transition is observed in the resistivity measurements for the alloys with x ≤ 0.5 [19]. Furthermore, the inset to Fig.…”

“…As already mentioned above, the end compounds of the series Pr 1−x Eu x Pt 4 Ge 12 are superconducting (x = 0) and antiferromagnetic (x = 1), respectively [10,13]. This fact alone naturally sets the stage for investigating the interplay between superconductivity and magnetism in this series of compounds [19]. In this paper, we report the results and analysis of the low-temperature specific heat measurements on Pr 1−x Eu x Pt 4 Ge 12 alloys subject to an external magnetic field.…”

“…Polycrystalline samples of Pr 1−x Eu x Pt 4 Ge 12 were synthesized by arc-melting and annealing according to the procedure described in detail in Ref. [19]. The crystal structure was determined by x-ray powder diffraction using a Bruker D8 Discover x-ray diffractometer with Cu-K α radiation [20].…”

“…The crystal structure was determined by x-ray powder diffraction using a Bruker D8 Discover x-ray diffractometer with Cu-K α radiation [20]. These polycrystalline samples were characterized through Rietveld refinement of powder Xray diffraction (XRD) data, as well as resistivity and magnetization measurements [19]. The x-ray diffraction patterns revealed that the polycrystalline samples used in this study are single phase.…”

“…The x-ray diffraction patterns revealed that the polycrystalline samples used in this study are single phase. The fact that the samples are really of the given compositions is shown by the linear dependence of the effective magnetic moment vs Eu-content x [19].…”