Z J Xiang

Coexistence of superconductivity and antiferromagnetism in single crystals A0.8Fe2?ySe2 (A=K, Rb, Cs, Tl/K and Tl/Rb): Evidence from magnetization and resistivity

We measure the resistivity and magnetic susceptibility in the temperature range from 5 K to 600 K for the single crystals AFe2−ySe2 (A=K0.8, Rb0.8, Cs0.8, Tl0.5K0.3 and Tl0.4Rb0.4). A sharp superconducting transition is observed in low-temperature resistivity and susceptibility, and the fully shielding fraction shows bulk susceptibility for all the crystals, while an antiferromagnetic transition is observed in susceptibility at Neel temperature (TN) as high as 500 K to 540 K depending on A. This indicates the coexistence of superconductivity and antiferromagnetism in these intercalated iron selenides. A sharp increase in resistivity arises from the structural transition due to Fe vacancy ordering at temperature slightly higher than TN. Occurrence of superconductivity in an antiferromagnetic ordered state with so high TN may suggest new physics in this type of unconventional superconductors.

Crystal structure, physical properties and superconductivity in AxFe2Se2 single crystals

We studied the correlation among structure, transport properties and superconductivity in different AxFe2Se2 single crystals (A=K, Rb and Cs). Two sets of (00l) reflections are observed in the x-ray single-crystal diffraction patterns, and they arise from the intrinsic inhomogeneous distribution of the intercalated alkali atoms. The occurrence of superconductivity is closely related to the c-axis lattice constant, and the A content is crucial to superconductivity. The hump observed in resistivity seems to be irrelevant to the superconductivity. There exist many deficiencies within the FeSe layers in AxFe2Se2, although their Tc does not change so much. In this sense, superconductivity is robust to the vacancies within the FeSe layers. Very high resistivity in the normal state should be ascribed to such defects in the conducting FeSe layers. AxFe2Se2 (A=K, Rb and Cs) single crystals show the same susceptibility behavior in the normal state, and no anomaly is observed in susceptibility at the hump temperature in resistivity. The clear jump in specific heat for RbxFe2Se2 and KxFe2Se2 single crystals indicates the good bulk superconductivity of these crystals.

Superconductivity and magnetic properties of single crystals of K 0 . 75 Fe 1 . 66 Se 2 and Cs 0 . 81 Fe 1 . 61 Se 2

We successfully grew the high-quality single crystals of

Isotropic superconductivity in LaRu2P2 with the ThCr2Si2-type structure

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A crossover in the phase diagram of NaFe1−xCoxAs determined by electronic transport measurements

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Transport properties and electronic phase diagram of cobalt-doped 1111-type iron arsenide hydride

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Phase diagram as a function of doping level and pressure in the Eu1-xLaxFe2As2 system

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Metal substitution effect on superconductivity in barium intercalated ternary metal nitride chlorides

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Incoherence–coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A = K, Rb, Cs): evidence from electrical transport properties

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Evolution of High-Temperature Superconductivity from a Low-T_{c} Phase Tuned by Carrier Concentration in FeSe Thin Flakes.

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