Saleem J. Denholme

Evolution of superconductivity in LaO1−xFxBiS2 prepared by high-pressure technique

Novel BiS2-based superconductors LaO1-xFxBiS2 prepared by the high pressure synthesis technique were systematically studied. It was found that the high pressure annealing strongly the lattice as compared to the LaO1-xFxBiS2 samples prepared by conventional solid state reaction at ambient pressure. Bulk superconductivity was observed within a wide F-concentration range of x = 0.2 ~ 0.7. On the basis of those results, we have established a phase diagram of LaO1-xFxBiS2.

Phase diagram and superconductivity at 58.1 K in α-FeAs-free SmFeAsO1−xFx

The phase diagram of SmFeAsO1−xFx in terms of x is exhibited in this study. Specimens of SmFeAsO1−xFx from x = 0 to x = 0.3 were prepared by low-temperature sintering with slow cooling. The low-temperature sintering suppresses the formation of the amorphous FeAs, which is inevitably produced as an impurity when using high-temperature sintering. Moreover, slow cooling is effective in obtaining a high fluorine concentration. The compositional change from feedstock composition is quite small after this synthesis. We can reproducibly observe a record superconducting transition for an iron-based superconductor at 58.1 K. This achievement of a high superconducting transition is due to the success in substituting a large amount of fluorine. A shrinking of the a lattice parameter caused by fluorine substitution is observed and the substitutional rate of fluorine changes at x = 0.16.

Clarification as to why alcoholic beverages have the ability to induce superconductivity in Fe1+dTe1?xSx

To elucidate the mechanism as to why alcoholic beverages can induce superconductivity in Fe1+dTe1?xSx samples, we performed component analysis and found that a weak acid such as an organic acid has the ability to induce superconductivity. Inductively coupled plasma spectroscopy was performed on weak acid solutions post-annealing. We found that the mechanism of inducement of superconductivity in Fe1+dTe1?xSx is the deintercalation of excess Fe from the interlayer sites.

High-Tc Phase of PrO0.5F0.5BiS2 single crystal induced by uniaxial pressure

We demonstrated a pressure-induced phase transition from a low-Tc phase (3.5 K) to a high-Tc phase (8.7 K) in single crystalline PrO0.5F0.5BiS2. The high-Tc phase is easily observed even at 0.7 GPa by uniaxial pressure obtained from a geometric effect of a single crystal with an extremely-thin thickness. For this phase transition, superconducting anisotropy and the coherence length along the c axis change from {\gamma} = 20 to 9.3 and from {\xi}c = 0.56 to 0.71 nm respectively. It is suggested that a shrinkage in the c lattice constant by applied uniaxial pressure enhances the three dimensionality in the superconducting state.

Site selectivity on chalcogen atoms in superconducting La(O,F)BiSSe

Single crystals of La(O,F)BiSSe were successfully grown by a CsCl flux method. Single crystal X-ray structural analysis revealed that the crystal structure is isostructural with BiS

Pressure-dependent magnetization and magnetoresistivity studies on tetragonal FeS (mackinawite): revealing its intrinsic metallic character

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Pressure-induced phase transition for single-crystalline LaO0.5F0.5BiSe2

- or BiSe

Origin of the Higher-Tc Phase in the KxFe2−ySe2 System

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Evolution of superconductivity in isovalent Te-substituted KxFe2−ySe2 crystals

-based compounds with space group

Excess iron deintercalation induced superconductivity in Fe(Te, Se) and Fe(Te, S) via sulfur annealing

P4/nmm