Evidence for unconventional superconducting fluctuations in heavy-fermion compound CeNi2Ge2

Abstract

We present evidence for unconventional superconducting fluctuations in a heavy-fermion compound CeNi${}_2$Ge${}_2$. The temperature dependence of the ${}^{73}$Ge nuclear-spin-lattice-relaxation rate $1/T_1$ indicates the development of magnetic correlations and the formation of a Fermi-liquid state at temperatures lower than $T_{\mathrm{FL}}=0.4$ K, where $1/T_{1}T$ is constant. The resistance and $1/T_{1}T$ measured on an as-grown sample decrease below $T_{\mathrm{c}}^{\mathrm{onset}}=0.2$ K and $T_{\mathrm{c}}^{\mathrm{NQR}}=0.1$ K, respectively; these are indicative of the onset of superconductivity. However, after annealing the sample to improve its quality, these superconducting signatures disappear. These results are consistent with the emergence of unconventional superconducting fluctuations in close proximity to a quantum critical point from the superconducting to the normal phase in CeNi${}_2$Ge${}_2$.

arXiv comment4pages,5figures,to appear in J. Phys. Soc. Jpn

References in corpus (5)

• Enhanced Valence Fluctuations Caused by f-c Coulomb Interaction in Ce-Based Heavy Electrons: Possible Origin of Pressure-Induced Enhancement of Superconducting Transition Temperature in \Ge and Related Compounds
• New Superconducting and Magnetic Phases Emerge on the Verge of Antiferromagnetism in CeIn${}_3$
• Unconventional Superconductivity in Heavy Fermion Systems
• ^{115}In-NQR evidence for unconventional superconductivity in CeIn_3 under pressure
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