Signatures of quantum criticality in the thermopower of Ba(Fe1-xCox)2As2

被引：27
作者：
Arsenijevic, S. [1 ,2 ]
Hodovanets, H. [3 ,4 ]
Gaal, R. [1 ]
Forro, L. [1 ]
Bud'ko, S. L. [3 ,4 ]
Canfield, P. C. [3 ,4 ]
机构：
[1] Ecole Polytech Fed Lausanne, Swiss Fed Inst Technol, Inst Condensed Matter Phys, CH-1015 Lausanne, Switzerland
[2] LNCMI CNRS, Lab Natl Champs Magnet Intenses, F-38042 Grenoble, France
[3] US DOE, Ames Lab, Ames, IA 50011 USA
[4] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA
来源：
PHYSICAL REVIEW B | 2013年 / 87卷 / 22期
关键词：
FERMI-LIQUID BEHAVIOR; RESISTIVITY; TEMPERATURE; SUPERCONDUCTIVITY; TRANSITION; ENTROPY;
D O I：
10.1103/PhysRevB.87.224508
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
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-x Co-x)(2)As-2 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 < x < 0.1 is bordered by two Lifshitz transitions, and it corresponds to the superconducting region, where a similarity between the electron and nonreconstructed hole pockets exists. The maximal S/T is observed in proximity to the commensurate-to-incommensurate SDW transition, for critical x(c) approximate to 0.05, close to the highest superconducting T-c. This analysis indicates that low-T thermopower is influenced by critical spin fluctuations which are important for the superconducting mechanism.
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页数：7
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