| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Outline of Final Research Achievements |
We report a 125Te-NMR study of single-crystalline Pb1-xTlxTe, revealing an increase in the average density of states (DOS) coupled to a strong spatial variation in the local DOS surrounding each Tl dopant. For the superconducting composition, the nuclear spin relaxation rate for Te ions that are close to the Tl dopants is unexpectedly enhanced in the normal state below a characteristic temperature of 10 K. This temperature coincides exactly with the temperature below which the normal state resistivity experiences an upturn. These observations provide microscopic evidence for dynamical charge fluctuations, and is consistent with expectations for charge Kondo behavior associated with the Tl dopant ions. In contrast, such anomalies were not detected in the non-superconducting samples, suggesting a connection between dynamical valence fluctuations and the occurrence of superconductivity in Pb1-xTlxTe.
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