Anisotropic Superconducting Gap in Transuranium Superconductor PuRhGa_5 : Ga NQR Study on a Single Crystal(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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^<69,71>Ga NMR/NQR studies have been performed on a single crystal of the transuranium superconductor PuRhGa_5 with T_c≃9K. We have observed a ^<69>Ga NQR line at 〜29.15MHz, and assigned it to the 4i Ga site using the NMR results. The ^<69>Ga NQR spin-lattice relaxation rate 1/T_1 shows no coherence peak just below T_c, but obeys T^3 behavior below T_c. This result strongly suggests that PuRhGa_5 is an unconventional superconductor having an anisotropic superconducting gap. The gap amplitude 2△_0(T→0)≃5k_BT_c and the residual density of states N_<res>(T=0)/N_0(T=T_c)≃0.25 have been determined assuming a simple polar function of the form △(θ, φ)=△_0cosθ, where θ and φ are angular parameters on the Fermi surface.
社団法人日本物理学会の論文
2005-06-15