Quantum Criticality and Nodal Superconductivity in the FeAs-Based Superconductor KFe2As2
Source: Phys. Rev. Lett. 104, 087005 (2010); doi:10.1103/PhysRevLett.104.087005
Published 26 February 2010
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The in-plane resistivity 
and thermal conductivity 
of the FeAs-based superconductor KFe2As2 single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior (T)~T1.5 at Hc2=5 T, and the development of a Fermi liquid state with (T)~T2 when further increasing the field. This suggests a field-induced quantum critical point, occurring at the superconducting upper critical field Hc2. In zero field, there is a large residual linear term 0/T, and the field dependence of 0/T mimics that in d-wave cuprate superconductors. This indicates that the superconducting gaps in KFe2As2 have nodes, likely d-wave symmetry. Such a nodal superconductivity is attributed to the antiferromagnetic spin fluctuations near the quantum critical point.
©2010 The American Physical Society
and thermal conductivity of the FeAs-based superconductor KFe2As2 single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior (T)~T1.5 at Hc2=5 T, and the development of a Fermi liquid state with (T)~T2 when further increasing the field. This suggests a field-induced quantum critical point, occurring at the superconducting upper critical field Hc2. In zero field, there is a large residual linear term 0/T, and the field dependence of 0/T mimics that in d-wave cuprate superconductors. This indicates that the superconducting gaps in KFe2As2 have nodes, likely d-wave symmetry. Such a nodal superconductivity is attributed to the antiferromagnetic spin fluctuations near the quantum critical point.
©2010 The American Physical Society
| History: | Received 4 January 2010; published 26 February 2010 |
| Permalink: |
http://link.aps.org/abstract/PRL/v104/e087005 |
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