Optical conductivity of FeTe1−xSex

The ab-plane optical conductivity of two single crystals belonging to the chalcogenide family, FeTe0.91 and FeTe0.7Se0.3, has been studied in the normal phase between 16 and 450 K. Several differences with respect to both conventional metals and other exotic superconductors, like the cuprates, have been found both in the undoped and in the doped material. In the former compound, the transition to an antiferromagnetic (AF) state at 67 K causes the opening of a pseudogap at ω0 = 270 ± 25 cm−1 and a decrease by 70% in the free carrier density, accompanied by a strong reduction in the carrier scattering rate. The multiband analysis of the low-energy optical conductivity requires at least two Drude components, in addition to a mid-infrared band. Above 350 K, a transfer of spectral weight between those terms produces a cusp anomaly in the spectral weight. This indicates a well-defined transition, rather than a crossover, to a less-metallic regime. Finally, in FeTe0.7Se0.3 the far-infrared conductivity decreases with T, in agreement with the semiconducting behavior of the resistivity, and precursor phenomena of superconductivity appear above Tc.

[1]  J. Storey,et al.  Evidence of a precursor superconducting phase at temperatures as high as 180 K in RBa2Cu3O(7-δ) (R=Y, Gd, Eu) superconducting crystals from infrared spectroscopy. , 2011, Physical review letters.

[2]  T. Qian,et al.  Angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3: strong coupling behavior and the universality of interband scattering. , 2010, Physical review letters.

[3]  D.Wu,et al.  Nodes in the order parameter of superconducting iron pnictides investigated by infrared spectroscopy , 2010, 1007.5215.

[4]  K. H. Kim,et al.  Dual character of magnetism in EuFe2AS2: Optical spectroscopic and density-functional calculation study , 2010 .

[5]  E. Giannini,et al.  Spin Glass ground state in Mn$_{1-x}$Co$_{x}$Si , 2010, 1004.5182.

[6]  M. Dressel,et al.  Electrodynamics of electron doped iron-pnictide superconductors: Normal state properties , 2010, 1004.1658.

[7]  E. Giannini,et al.  Strong coupling to magnetic fluctuations in the charge dynamics of iron-based superconductors , 2010, 1004.0111.

[8]  A. Georges,et al.  Theoretical evidence for strong correlations and incoherent metallic state in FeSe , 2010, 1003.1286.

[9]  C. Bark,et al.  Multi-gap superconductivity in a BaFe1.84Co0.16As2 film from optical measurements at terahertz frequencies , 2010, 1003.0565.

[10]  G. Gu,et al.  Electronic Correlations and Unusual Superconducting Response in the Optical Properties of the Iron Chalcogenide FeTe0.55Se0.45 , 2010, 1002.4846.

[11]  L. Kohlman,et al.  Normal state charge dynamics of Fe1.06Te0.88S0.14 superconductor probed with infrared spectroscopy , 2010, 1002.1948.

[12]  A. Palenzona,et al.  Transport and superconducting properties of Fe-based superconductors: a comparison between SmFeAsO1−xFx and Fe1+yTe1−xSex , 2009, 0912.0395.

[13]  D. Marel,et al.  Seebeck effect in Fe1+xTe1-ySey single-crystals, , 2009, 0910.0191.

[14]  D. Basov,et al.  Electronic correlations in the iron pnictides , 2009, 0909.0312.

[15]  K. Yeh,et al.  Superconducting FeSe1−xTex Single Crystals Grown by Optical Zone-Melting Technique , 2009, 0908.2855.

[16]  A. Amato,et al.  Coexistence of incommensurate magnetism and superconductivity in Fe1+ySexTe1-x , 2009, 0907.3429.

[17]  L. Kohlman,et al.  Signatures of electron-boson coupling in the half-metallic ferromagnet Mn 5 Ge 3 : Study of electron self-energy Σ(ω) obtained from infrared spectroscopy , 2009, 0905.3731.

[18]  A. Faridian,et al.  Effects of magnetic ordering on dynamical conductivity: Optical investigations ofEuFe2As2single crystals , 2009, 0903.0575.

[19]  A. Sefat,et al.  Bulk Superconductivity at 14 K in Single Crystals of Fe1+yTexSe1-x , 2009, 0902.1519.

[20]  N. L. Wang,et al.  Optical and Raman spectroscopy studies on Fe-based superconductors , 2009, 0902.0435.

[21]  Jiangping Hu,et al.  First-order magnetic and structural phase transitions in Fe1+ySexTe1-x , 2008, 0811.0195.

[22]  B. Keimer,et al.  Signatures of electronic correlations in optical properties of LaFeAsO1-xFx. , 2008, Physical review letters.

[23]  G. Li,et al.  Electronic properties of single-crystalline Fe$_{1.05}$Te and Fe$_{1.03}$Se$_{0.30}$Te$_{0.70}$ , 2008, 0811.1489.

[24]  G. Profeta,et al.  The optical phonon spectrum of SmFeAsO , 2008, 0810.2176.

[25]  David J. Singh,et al.  Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity , 2008, 0807.4312.

[26]  L. Baldassarre,et al.  Quasiparticle evolution and pseudogap formation in V 2 O 3 : An infrared spectroscopy study , 2007, 0710.1247.

[27]  S. Dordevic,et al.  Electrodynamics of correlated electron matter , 2005, cond-mat/0510351.

[28]  D. Basov,et al.  Electrodynamics of high- T c superconductors , 2005 .

[29]  P. Calvani,et al.  Frequency-dependent thermal response of the charge system and the restricted sum rules of La2-xSrxCuO4. , 2004, Physical review letters.

[30]  G. Grüner,et al.  Density Waves In Solids , 1994 .