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Non-Fermi liquid normal-state properties and unconventional superconductivity in Fe-pnictide superconductors

Takasada Shibauchi Department of Physics, Kyoto University Sakyo-ku, Kyoto 606-8502, Japan - Email : shibauchi@scphys.kyoto-u.ac.jp


I will introduce our recent results on the superconducting pairing
symmetries [1-4] and normal-state transport properties [5] in the recently
discovered Fe-pnictide high temperature superconductors. The magnetic
penetration depth [1,3] and lower critical field measurements [2]
consistently show the fully gapped superconducting state in Fe-arsenides
PrAsFeO_1-y and (Ba,K)Fe2As2. In contrast, the phosphide LaFePO with
lower Tc (=7 K) is found to have nodes by thermal conductivity
measurements, which is consistent with the recent penetration depth
measurements [6,7]. These results point to the unconventional
superconducting symmetries which have nearly degenerated two channels for
the leading pairing instability. The normal state transport properties
measured in high-quality single crystals of BaFe2(As,P)2 reveal that the
striking T-linear resistivity and strongly temperature dependent Hall
coefficient near the boundary of spin density wave and superconductivity
phases. Such a non-Fermi liquid properties seem to be generic to the
correlated electron systems in the presence of anti-ferromagnetic spin
fluctuations, which may act as glues for Cooper pairing in unconventional
superconductors.

 

[1] K. Hashimoto et al., Phys. Rev. Lett. 102, 017002 (2009).

[2] R. Okazaki et al., Phys. Rev. B 79, 064520 (2009).

[3] K. Hashimoto et al., Phys. Rev. Lett. 102, 207001 (2009).

[4] M. Yamashita et al., arXiv:0906.0622.

[5] S. Kasahara et al., arXiv:0905.4427.

[6] J. D. Fletcher et al., Phys. Rev. Lett. 102, 147001 (2009).

[7] C. W. Hicks et al., arXiv:0903.5260.

 

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