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تسجيل مستخدم جديدEvidence for s-wave superconductivity in the new beta-pyrochlore oxide RbOs2O6
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We report the results of 87Rb NMR measurements on RbOs2O6, a new member of the family of the superconducting pyrochlore-type oxides with a critical temperature Tc = 6.4 K. In the normal state, the nuclear spin-lattice relaxation time T1 obeys the Korringa-type relation T1T = constant and the Knight shift is independent of temperature, indicating the absence of strong magnetic correlations. In the superconducting state, T1^{-1}(T) exhibits a tiny coherence enhancement just below Tc, and decreases exponentially with further decreasing temperatures. The value of the corresponding energy gap is close to that predicted by the conventional weak-coupling BCS theory. Our results indicate that RbOs2O6 is a conventional s-wave-type superconductor.
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Two beta-pyrochlore oxide superconductors, CsOs2O6 and RbOs2O6, are studied thermodynamically by measuring specific heat on polycrystalline samples. It is found that a Sommerfeld coefficient ? is nearly equal, 20 mJ/K2 mol Os, in the two oxides with
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