期刊
PHYSICAL REVIEW B
卷 83, 期 6, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.83.064513
关键词
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资金
- US Department of Energy, Office of Science
- Los Alamos LDRD program
- Materials Sciences and Engineering Division, Office of Basic Energy Sciences, US Department of Energy
- DOE [DE-FG02-08ER46492]
- NSF [DMR-0954342]
- NSERC
- CFI
- CIFAR
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0954342] Funding Source: National Science Foundation
We report on the effect of annealing on the temperature and field dependencies of the low-temperature specific heat of the electron-doped Ba(Fe1-xCox)(2)As-2 for under- (x = 0.045), optimally (x = 0.08), and over-(x = 0.105 and 0.14) doped regimes. We observed that annealing significantly improves some superconducting characteristics in Ba(Fe1-xCox)(2)As-2. It considerably increases T-c, decreases gamma(0) in the superconducting state, and suppresses the Schottky-like contribution at very low temperatures. The improved sample quality allows for a better identification of the superconducting gap structure of these materials. We examine the effects of doping and annealing within a self-consistent framework for an extended s-wave pairing scenario. At optimal doping our data indicate that the sample is fully gapped, while for both under- and overdoped samples significant low-energy excitations remain, possibly consistent with a nodal structure. The difference of sample quality offers a natural explanation for the variation in low-temperature power laws observed by many techniques.
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