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Among the family of TMDs, ReS2 takes a special position, which crystalizes in a unique distorted low-symmetry structure at ambient conditions. The interlayer interaction in ReS2 is rather weak, thus its bulk properties are similar to that…

Polycrystalline samples with nominal composition of Ba(Fe1-xIrx)2As2 (x=0.10, 0.15, and 0.20) were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), electrical resistivity, and magnetization measurements.…

Superconductivity · Physics 2015-05-14 X. L. Wang , H. Y. Shi , X. W. Yan , Y. C. Yuan , Z. -Y. Lu , X. Q. Wang , T. -S. Zhao*

The newly discovered BaPt$_2$As$_2$ shows a structural distortion at around 275~K, followed by the emergence of superconductivity at lower temperatures. Here we identify the presence of charge density wave (CDW) order at room temperature…

Superconductivity · Physics 2016-11-18 C. Y. Guo , W. B. Jiang , M. Smidman , F. Han , C. D. Malliakas , B. Shen , Y. F. Wang , Y. Chen , X. Lu , M. G. Kanatzidis , H. Q. Yuan

Single crystals of superconducting BaFe$_{1.8}$Co$_{0.2}$As$_2$ were exposed to neutron irradiation in a fission reactor. The introduced defects decrease the superconducting transition temperature (by about 0.3 K) and the upper critical…

Superconductivity · Physics 2015-05-13 M. Eisterer , M. Zehetmayer , H. W. Weber , J. Jiang , J. D. Weiss , A. Yamamoto , E. E. Hellstrom

The magnetic order of the localized Eu$^{2+}$ spins in optimally-doped Eu(Fe$_{1-x}$Ir$_{x}$)$_{2}$As$_{2}$ ($\mathit{x}$ = 0.12) with superconducting transition temperature $\mathit{T_{SC}}$ = 22 K was investigated by single-crystal…

Superconductivity · Physics 2015-02-20 W. T. Jin , Wei Li , Y. Su , S. Nandi , Y. Xiao , W. H. Jiao , M. Meven , A. P. Sazonov , E. Feng , Yan Chen , C. S. Ting , G. H. Cao , Th. Brückel

Transition metal ditellurides with the CdI2-type structure are materials with intriguing superconducting and electronic properties as demonstrated by PdTe2. Gold substituted PdTe2, AuxPd1-xTe2, adopts the CdI2-type structure for a Pd…

We use neutron scattering to study the spin and lattice structures of single crystal and powder samples of Na$_{1-\delta}$FeAs ($T_c = 23$ K). On cooling from room temperature, the system goes through a series of phase transitions: first…

Superconductivity · Physics 2009-07-10 Shiliang Li , Clarina de la Cruz , Q. Huang , G. F. Chen , T. -L. Xia , J. L. Lou , N. L. Wang , Pengcheng Dai

We have investigated uniaxial and hydrostatic pressure effects on superconductivity in Fe1.07Te0.88S0.12 through magnetic-susceptibility measurements down to 1.8 K. The superconducting transition temperature Tc is enhanced by out-of-plane…

A new hight Tc Fe-based compound system, AFe2As2 with A = K, Cs, K/Sr and Cs/Sr has been found. Through electron-doping, Tc of the A = K and Cs compounds rises to ~37 K, and finally enter a spin-density-wave state (SDW) through further…

Superconductivity · Physics 2008-09-09 K. Sasmal , B. Lv , B. Lorenz , A. Guloy , F. Chen , Y. Xue , C. W. Chu

Structural, magnetic, electrical transport, and heat capacity data are reported for single crystals of TlFe1.6Se2. This compound crystallizes in a tetragonal structure similar to the ThCr2Si2 structure, but with vacancies in the Fe layer.…

CaFe$_2$As$_2$ has been synthesized and found to form in the tetragonal, ThCr$_2$Si$_2$ structure with lattice parameters $a = 3.912(68) \AA$ and $c = 11.667(45) \AA$. Upon cooling through 170 K, CaFe$_2$As$_2$ undergoes a first order,…

Strongly Correlated Electrons · Physics 2009-11-13 N. Ni , S. Nandi , A. Kreyssig , A. I. Goldman , E. D. Mun , S. L. Bud'ko , P. C. Canfield

We report specific-heat experiments under the influence of high pressure on a strongly underdoped Co-substituted BaFe2As2 single crystal. This allows us to study the phase diagram of this iron pnictide superconductor with a bulk…

Superconductivity · Physics 2015-06-12 Yan Zheng , Yuxing Wang , Frederic Hardy , Anna E. Böhmer , Thomas Wolf , Christoph Meingast , Rolf Lortz

We study the structural and magnetic orders in electron-doped BaFe2-xNixAs2 by high-resolution synchrotron X-ray and neutron scatterings. Upon Ni-doping x, the nearly simultaneous tetragonal-to-orthorhombic structural T_s and…

We report anisotropic dc magnetic susceptibility $\chi(T)$, electrical resistivity $\rho(T)$, and heat capacity $C(T)$ measurements on the single crystals of CaFe$_{2-x}$Co$_x$As$_2$ for $x$ = 0 and 0.06. Large sized single crystals were…

Superconductivity · Physics 2009-11-13 Neeraj Kumar , R. Nagalakshmi , R. Kulkarni , P. L. Paulose , A. K. Nigam , S. K. Dhar , A. Thamizhavel

We have successfully synthesized the fluoride-arsenide compounds Ca$_{1-x}$RE$_x$FeAsF (RE=Nd, Pr; x=0, 0.6). The x-ray powder diffraction confirmed that the main phases of our samples are Ca$_{1-x}$RE$_x$FeAsF with the ZrCuSiAs structure.…

Superconductivity · Physics 2009-04-23 Peng Cheng , Bing Shen , Gang Mu , Xiyu Zhu , Fei Han , Bin Zeng , Hai-Hu Wen

The structural properties of EuCo2As2 have been studied up to 35 GPa, through the use of x-ray diffraction in a diamond anvil cell at a synchrotron source. At ambient conditions, EuCo2As2 (I4/mmm) has a tetragonal lattice structure with a…

Materials Science · Physics 2011-04-19 Matthew Bishop , Walter Uhoya , Georgiy Tsoi , Yogesh K. Vohra , Athena S. Sefat , Brian C. Sales

Superconductors close to quantum phase transitions often exhibit a simultaneous increase of electronic correlations and superconducting transition temperatures. Typical examples are given by the recently discovered iron-based…

The temperature dependence of in plane optical conductivity has been investigated for Ca0.86Pr0.14Fe2As2 which shows a structural transition from tetragonal (T) to collapsed tetragonal(cT) phase at TcT=73 K. Upon entering the cT phase,…

Superconductivity · Physics 2015-06-17 Run Yang , Congcong Le , Lei Zhang , Bing Xu , Wei Zhang , Kashif Nadeem , Hong Xiao , Jiangping Hu , Xianggang Qiu

Here we report bulk superconductivity in BaFe1.8Co0.2As2 single crystals below Tc = 22 K, as demonstrated by resistivity, magnetic susceptibility, and specific heat data. Hall data indicate that the dominant carriers are electrons, as…

X-ray diffraction experiments were performed on polycrystalline and single-crystal specimens of Ce$_{2}$Fe$_{17}$ at temperatures between 10 K and 300 K. Below $T_{\mathrm{t}}$ = 118$\pm$2 K, additional weak superstructure reflections were…