Effect of annealing on the specific heat of Ba(Fe1-xCox)2As2

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.83.064513· OSTI ID:1010597

Gofryk, K ^[1]; Vorontsov, A B ^[2]; Vekhter, I ^[3]; Sefat, A. S. ^[4]; Imai, T. ^[5]; Bauer, E. D. ^[1]; Thompson, J. D. ^[1]; Ronning, F. ^[1]

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1. Los Alamos National Laboratory (LANL)
2. Montana State University
3. Louisiana State University
4. Oak Ridge National Laboratory (ORNL)
5. McMaster University

We report on the effect of annealing on the temperature and field dependencies of the low-temperature specific heat of the electron-doped Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 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(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. It considerably increases T{sub c}, decreases {gamma}{sub 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.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1010597
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 6 Vol. 83; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
ARSENIDES
BARIUM COMPOUNDS
COBALT ARSENIDES
DOPED MATERIALS
IRON ARSENIDES
SPECIFIC HEAT
SUPERCONDUCTIVITY
TRANSITION TEMPERATURE