Signatures of quantum criticality in the thermopower of Ba(Fe1-xCox)(2)As-2
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Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
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Abstract
We demonstrate that the thermopower (S) can be used to probe the spin fluctuations (SFs) in proximity to the quantum critical point (QCP) in Fe-based superconductors. The sensitivity of S to the entropy of charge carriers allows us to observe an increase of S/T in Ba(Fe1−xCox)2As2 close to the spin-density-wave (SDW) QCP. This behavior is due to the coupling of low-energy conduction electrons to two-dimensional SFs, similar to heavy-fermion systems. The low-temperature enhancement of S/T in the Co substitution range 0.02
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This article is published as Arsenijević, S., H. Hodovanets, R. Gaál, L. Forró, S. L. Bud'Ko, and P. C. Canfield. "Signatures of quantum criticality in the thermopower of Ba (Fe 1− x Co x) 2 As 2." Physical Review B 87, no. 22 (2013): 224508. DOI: 10.1103/PhysRevB.87.224508. Posted with permission.