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We report the crystal growth and structural, magnetic, conductivity, and specific heat investigations of Rb(1-x)Fe(2-y)Se2 single crystals with varying stoichiometry prepared by self-flux and Bridgman methods. The system exhibits a strongly…

Superconductivity · Physics 2011-11-01 V. Tsurkan , J. Deisenhofer , A. Günther , H. -A. Krug von Nidda , S. Widmann , A. Loidl

This paper discusses the synthesis, characterization, and comprehensive study of Ba-122 single crystals with various substitutions and various $T_c$. The paper uses five complementary techniques to obtain a self-consistent set of data on…

Large high-quality single crystals of hole-doped iron-based superconductor (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ were grown over a broad composition range $0.22 \leq x \leq 1$ by inverted temperature gradient method. We found that high soaking…

Systematic measurements of the resistivity, heat capacity, susceptibility and Hall coefficient are presented for single crystal samples of the electron-doped superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. These data delineate an $x-T$ phase…

Superconductivity · Physics 2009-05-02 Jiun-Haw Chu , James G. Analytis , Chris Kucharczyk , Ian R. Fisher

To explore the origin of the unusual non-bulk superconductivity with a Tc up to 49 K reported in the rare-earth-doped CaFe2As2 , the chemical composition, magnetization, specific heat, resistivity, and annealing effect are systematically…

Superconductivity · Physics 2016-03-02 L. Z. Deng , B. Lv , K. Zhao , F. Y. Wei , Y. Y. Xue , Z. Wu , C. W. Chu

Single crystals of Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$, $x<0.37$, have been grown and characterized by structural, magnetic and transport measurements. These measurements show that the structural/magnetic phase transition found in pure…

Superconductivity · Physics 2015-05-19 A. Thaler , N. Ni , A. Kracher , J. Q. Yan , S. L. Bud'ko , P. C. Canfield

We report magnetic penetration depth and thermal conductivity data for high-quality single crystals of BaFe$_2$(As$_{1-x}$P$_{x}$)$_2$ ($T_c=30$\,K) which provide strong evidence that this material has line nodes in its energy gap. This is…

We performed an optical spectroscopy measurement on single crystals of $\mathrm{Ba_2Ti_2Fe_2As_4O}$, which is a newly discovered superconductor showing a coexistence of superconductivity and density wave order. The study reveals a spectral…

Superconductivity · Physics 2015-06-22 H. P. Wang , Y. L. Sun , X. B. Wang , Y. Huang , T. Dong , R. Y. Chen , G. H. Cao , N. L. Wang

The mechanism of unconventional superconductivity in iron-based superconductors (IBSs) is one of the most intriguing questions in current materials research. Among non-oxide IBSs, (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ has been intensively studied…

The thermal conductivity $\kappa$ of the iron-arsenide superconductor Ba$_{1-x}$K$_x$Fe$_2$As$_2$ ($T_c \simeq$ 30 K) was measured in single crystals at temperatures down to $T \simeq 50$ mK ($\simeq T_c$/600) and in magnetic fields up to…

The results of infrared reflectivity measurements for the iron-based high-temperature superconductor Ba(Fe0.9Co0.1)2As2 are reported. The reflectivity is found to be close to unity at frequencies w lower than 2Delta/h (2Delta is the…

Superconductivity · Physics 2012-01-13 Yu. A. Aleshchenko , A. V. Muratov , V. M. Pudalov , E. S. Zhukova , B. P. Gorshunov , F. Kurth , K. lida

Temperature dependent high pressure electrical resistivity studies has been carried out on Ba(Fe_{1-x}Ru_{x})_{2}As_{2} single crystals with x = 0.12, 0.26 and 0.35, which correspond to under doped, optimally doped and over doped…

Superconductivity · Physics 2014-02-17 T. R. Devidas , Awadhesh Mani , Shilpam Sharma , K. Vinod , A. Bharathi , C. S. Sundar

Using a differential technique, we have measured the specific heats of polycrystalline Ba1-xKxFe2As2 samples with x=0, 0.1 and 0.3, between 2K and 380K and in magnetic fields 0 to 13 Tesla. From this data we have determined the electronic…

Superconductivity · Physics 2010-01-05 J. G. Storey , J. W. Loram , J. R. Cooper , Z. Bukowski , J. Karpinski

We have systematically investigated the doping and the directional dependence of the gap structure in the 122-type iron pnictide superconductors by point contact Andreev reflection spectroscopy. The studies were performed on single crystals…

F-doped LaOBiSe$_{2}$ superconducting single crystals with typical size of 2$\times$4$\times$0.2 mm$^{3}$ are successfully grown by flux method and the superconducting properties are studied. Both the superconducting transition temperature…

Superconductivity · Physics 2014-08-12 Jifeng Shao , Zhongheng Liu , Xiong Yao , Lei Zhang , Li Pi , Shun Tan , Changjin Zhang , Yuheng Zhang

Temperature-dependent reflectivity measurements in the frequency range 85 - 7000 cm$^{-1}$ were performed on BaFe$_2$As$_2$ single crystals under pressure up to $\sim$5 GPa. The corresponding pressure- and temperature-dependent optical…

Superconductivity · Physics 2016-01-20 E. Uykur , T. Kobayashi , W. Hirata , S. Miyasaka , S. Tajima , C. A. Kuntscher

We have measured the complex dynamical conductivity, $\sigma = \sigma_{1} + i\sigma_{2}$, of superconducting Ba(Fe$_{0.9}$Co$_{0.1}$)$_{2}$As$_{2}$ ($T_{c} = 22$ K) at terahertz frequencies and temperatures 2 - 30 K. In the frequency…

Superconductivity · Physics 2015-05-18 T. Fischer , A. V. Pronin , J. Wosnitza , K. Iida , F. Kurth , S. Haindl , L. Schultz , B. Holzapfel , E. Schachinger

The characteristics of Fe-based superconductors are manifested in their electronic, magnetic properties, and pairing symmetry of the Cooper pair, but the latter remain to be explored. Usually in these materials, superconductivity coexists…

To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe_2, comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields…

Superconductivity · Physics 2009-11-13 C. L. Huang , J. -Y. Lin , Y. T. Chang , C. P. Sun , H. Y. Shen , C. C. Chou , H. Berger , T. K. Lee , H. D. Yang

We measured the resistivity and magnetic susceptibility to map out the phase diagram of single crystalline NaFe$_{1-x}$Co$_x$As. Replacement of Fe by Co suppresses both the structural and magnetic transition, while enhances the…

Superconductivity · Physics 2012-06-21 A. F. Wang , X. G. Luo , Y. J. Yan , J. J. Ying , Z. J. Xiang , G. J. Ye , P. Cheng , Z. Y. Li , W. J. Hu , X. H. Chen