engleski

Fermi-liquid resistvity in the normal state of iron-pnictides

It became apparent recently that the superconducting state in iron-pnictides is complex because several electronic bands are involved. However, when discussing other different physical properties, in particular those related to the “non-Fermi liquid” regime, this important fact is often omitted. Our analysis of the optical conductivity in the normal and broken-symmetry (spin-density-wave (SDW) and superconducting) ground states elucidates the general [1] electrodynamical properties of iron-pnictides. Two sorts of charge carriers are discerned connected to the two different portions of the Fermi surface. One sort is approximately temperature and material independent, exhibiting a large scattering rate. The second governs the temperature and frequency dependences of the electrical properties in iron-pnictides. It becomes gapped due to the SDW transition in the parent materials [2], or alternatively it is driving the superconductivity in doped compounds [3]. Analyzing the dc resistivity in a novel way by separating two conducting channels reveals a hidden T2 dependence over a wide temperature range ; such a Fermi-liquid like behavior poses strong constrains on understanding of these materials. Recently, quadratic temperature dependence of the resistivity in the pseudogaped phase of HgBa2CuO4+δ [4], which is considered to be a model cuprate superconductor [5], was also observed. This, together with the results obtained on iron-pnictides, point towards common features in the description of electronic properties of unconventional superconductors. [1] N. Barišić, D. Wu, M. Dressel, L. J. Li, G. H. Cao and Z. A. Xu. Phys. Rev. B 82, 054518 (2010) [2] D. Wu, N. Barišić, N. Drichko, S. Kaiser, A. Faridian, M. Dressel, S. Jiang, Z. Ren, L. J. Li, G. H. Cao, Z. A. Xu, H. S. Jeevan and P. Gegenwart. Phys. Rev. B 79, 155103 (2009). [3] D. Wu, N. Barišić, P. Kallina, A. Faridian, B. Gorshunov, N. Drichko, L. J. Li, G. H. Cao, Z. A. Xu, N. L. Wang, and M. Dressel. Phys. Rev. B 81, 100512(R) (2010). [4] N. Barišić, Y. Li, G. Yu, X. Zhao, A. Smontara, M. Dressel, M. Greven. Manuscript in preparation. [5] N. Barišić, Y. Li, X. Zhao, Y. –C. Cho, G. Chabot-Couture, G. Yu, and M. Greven. Phys. Rev. B 78, 054518 (2008).

iron-pnictides; electrical properties; optical conductivity

The paper was presented as a talk by Neven Barišić.