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To clarify superconductivity in EuFe2As2 hidden by antiferromagnetism of Eu2+, we investigated a Ca-substituted sample, Eu0.5Ca0.5Fe2As2, under high pressure. For ambient pressure, the sample exhibits a spin-density-wave (SDW) transition at…

Superconductivity · Physics 2010-07-13 Akihiro Mitsuda , Tomohiro Matoba , Hirofumi Wada , Fumihiro Ishikawa , Yuh Yamada

Fe-K$_{\beta}$ X-ray emission spectroscopy measurements reveal an asymmetric doping dependence of the magnetic moments $\mu_\text{bare}$ in electron- and hole-doped BaFe$_{2}$As$_{2}$. At low temperature, $\mu_\text{bare}$ is nearly…

A series of 122 phase BaFe$_{2-x}$Ni$_x$As$_2$ ($x$ = 0, 0.055, 0.096, 0.18, 0.23) single crystals were grown by self flux method and a dome-like Ni doping dependence of superconducting transition temperature is discovered. The transition…

Superconductivity · Physics 2009-02-27 L. J. Li , Q. B. Wang , Y. K. Luo , H. Chen , Q. Tao , Y. K. Li , X. Lin , M. He , Z. W. Zhu , G. H. Cao , Z. A. Xu

The percentage of substitutional doping of magnetic atoms (Mn) in group-IV-based dilute magnetic semiconductors (DMS) can be increased by co-doping with another conventional electronic dopant (e-dopant) [Zhu et al., Phys. Rev. Lett. 100,…

Materials Science · Physics 2009-06-04 Hua Chen , Wenguang Zhu , Efthimios Kaxiras , Zhenyu Zhang

Of all parent compounds of iron-based high-temperature superconductors, EuFe2As2 exhibits by far the largest magnetostructural coupling due to the sizable biquadratic interaction between Eu and Fe moments. While the coupling between Eu…

We have investigated experimentally how properties of NdFeAsO0.8F0.2 superconductor affected due to the substitution of the Ca2+/Nd3+ doping. Based on the XRD data refinement, various structural parameters such as lattice parameters, bond…

Superconductivity · Physics 2019-05-29 F. Shahbaz Tehrani , V. Daadmehr

We study experimentally and theoretically the effect of Eu doping and partial oxygen isotope substitution on the transport and magnetic characteristics and spin-state transitions in (Pr$_{1-y}$Eu$_y$)$_{0.7}$Ca$_{0.3}$CoO$_3$ cobaltites.…

Resistivity, Hall effect and magnetoresistance have been investigated systematically on single crystals of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ ranging from undoped to optimally doped regions. A systematic evolution of the quasiparticle scattering…

Superconductivity · Physics 2011-11-24 Bing Shen , Huan Yang , Zhao-Sheng Wang , Fei Han , Bin Zeng , Lei Shan , Cong Ren , Hai-Hu Wen

We report the effect of 3d metal Cobalt (Co) and Nickel (Ni) doping on the FeTe0.5Se0.5 superconductor with the nominal composition range Fe1-xMxTe0.5Se0.5 (M = Co, Ni and x = 0.00, 0.01 0.02, 0.05, and 0.10). Samples are synthesized…

Superconductivity · Physics 2012-11-21 Anuj Kumar , R. P. Tandon , V. P. S. Awana

We demonstrate the preparation of large, free standing iron pnictide single crystals with a size up to 20 x 10 x 1 mm3 using solvents in zirconia crucibles under argon atmosphere. Transport and magnetic properties are investigated to study…

Superconductivity · Physics 2011-08-11 G. L. Sun , D. L. Sun , M. Konuma , P. Popovich , A. Boris , J. B. Peng , K. -Y. Choi , P. Lemmens , C. T. Lin

The structural, electrical and magnetic properties of the superconducting ferromagnets, Gd1.4-xDyxCe0.6Sr2RuCu2O10 (x=0-0.6) are systematically investigated as a function of Dy doping and temperature. These compounds are characterised by…

Superconductivity · Physics 2009-11-07 S. Kalavathi , J. Janaki , G. V. N. Rao , V. Sankara Sastry , Y. Hariharan

We report detailed measurements of composition as well as temperature dependence of the phonon density-of-states in a new series of FeAs compounds with composition CaFe1\_{1-x}Co\_{x}AsF (x = 0, 0.06, 0.12). The composition as well as…

We calculate the effect of local magnetic moments on the electron-phonon coupling in BaFe$_{2}$As$_{2}+\delta$ using the density functional perturbation theory. We show that the magnetism enhances the total electron-phonon coupling by $\sim…

Superconductivity · Physics 2010-09-13 Lilia Boeri , Matteo Calandra , Igor I. Mazin , Oleg V. Dolgov , Francesco Mauri

Using a combination of neutron, muon and synchrotron techniques we show how the magnetic state in NaFeAs can be tuned into superconductivity by replacing Fe by either Co or Ni. Electron count is the dominant factor, since Ni-doping has…

In this review, we present a summary of experimental studies of magnetism in Fe-based superconductors. The doping dependent phase diagram shows strong similarities to the generic phase diagram of the cuprates. Parent compounds exhibit…

Superconductivity · Physics 2010-05-19 M. D. Lumsden , A. D. Christianson

The vanadium doping effects on superconductivity and magnetism of iron pnictides are investigated in Ba(Fe$_{0.92-x}$Co$_{0.08}$V$_x$)$_2$As$_2$ by transport, susceptibility and neutron scattering measurements. The doping of magnetic…

We study the effect of hole-doping and chemical pressure (isovalent doping) in single crystals of K$_x$Eu$_{1-x}$Fe$_2$As$_2$ and EuFe$_2$(As$_{1-y}$P$_y$)$_2$, respectively, by measurements of the thermopower, $S(T)$, and electrical…

Strongly Correlated Electrons · Physics 2012-01-06 J. Maiwald , H. S. Jeevan , P. Gegenwart

An anisotropic Kondo semiconductor CeOs$_2$Al$_{10}$ exhibits an unusual antiferromagnetic order at rather high transition temperature $T_0$ of 28.5 K. Two possible origins of the magnetic order have been proposed so far, one is the Kondo…

Strongly Correlated Electrons · Physics 2016-11-18 Shin-ichi Kimura , Hitoshi Takao , Jo Kawabata , Yoshihiro Yamada , Toshiro Takabatake

We have investigated the impact of Ru substitution for Co on the behavior of the ferromagnetic superconductor UCoGe by performing x-ray diffraction, magnetization, specific heat and electrical resistivity measurements on polycrystalline…

Strongly Correlated Electrons · Physics 2015-08-03 Michal Vališka , Jiří Pospíšil , Vladimír Sechovský , Martin Diviš , Mohsen M. Abd-Elmeguid

We report bulk superconductivity (SC) in Eu$_{0.2}$Sr$_{0.8}$(Fe$_{0.86}$Co$_{0.14}$)$_{2}$As$_{2}$ single crystals by means of electrical resistivity, magnetic susceptibility, and specific heat measurements with $T$$_{\mathrm{c}}$ $\simeq$…

Superconductivity · Physics 2012-01-05 R. Sarkar , R. Nath , P. Khuntia , H. S. Jeevan , P. Gegenwart , M. Baenitz