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

Abstract

We discovered a novel annealing method for Fe-chalcogenide superconductors. It was found that sulfur annealing deintercalated excess Fe via formation of FeS 2 . Due to its specifics, sulfur annealing is applicable when preparing Fe-chalcogenide-based wires or cables.

Superconductivity in FeTe1−xSx Induced by Electrochemical Reaction Using Ionic Liquid Solution

“…8,9) So far, we have succeeded in inducing superconductivity in the 11-system compound by removing excess Fe from the interlayer by annealing in an organic acid solution, for instance in citric acid. [10][11][12][13] However, this reaction progresses slowly and is less tunable to induce superconductivity. More sophisticated methods of removing excess Fe are required.…”

“…This excess Fe suppresses superconductivity by doping the excess electrons to the superconducting layers [8,9]. So far, we have been succeeded in inducing superconductivity in the 11-system compound by removing excess Fe from the interlayer by annealing in an organic acid solution, for instance in a citric acid solution [10][11][12][13]. But this reaction progresses slowly and is less tunable to induce superconductivity.…”

Size Dependence of Oxygen-annealing Effects on Superconductivity of Fe{1+y}Te{1-x}S{x}

“…While as-grown samples of Fe 1+y Te 1−x S x exhibits no superconductivity for all the compositions of x and y, 9 superconductivity can be induced in Fe 1+y Te 1−x S x by several kinds of treatments. Examples of such treatments are leaving in the air for a long time, 10 annealing in O 2 atmosphere (O 2 annealing), [11][12][13] annealing in S atmosphere, 14 and soaking in hot alcoholic beverages or aqueous organic solutions, e.g. red wine or malic acid.…”

“…In another 11 system, Fe 1+y Te 1−x Se x , superconductivity can be also induced by various treatments. 14,[17][18][19][20][21] Among the treatments, annealing in low-pressure oxygen atmosphere or in vacuum can induce bulk superconductivity, and a large critical current density J c and a discontinuity of the specific heat have been observed. 17,18,20 By contrast, no evidence for bulk superconductivity in Fe 1+y Te 1−x S x has been observed thus far, although zero electrical resistivity and large diamagnetic susceptibility in zero-field-cooled (ZFC) condition have been observed in Fe 1+y Te 1−x S x samples after similar treatments.…”

Oxygen-annealing effects on superconductivity in polycrystalline Fe1+xTe1−ySey

“…Different post-preparation manipulations revealed significant influences on the superconducting properties of FeTe 1−y Se y . These treatments include exposure to HNO 3 [19], I 2 [20], O 2 [21], Te [22], and S [23] at ambient conditions or annealing at higher temperatures, as well as under N 2 [20] or vacuum [24]. Especially, annealing Fe 1+x Te 1−y Se y single crystals in an oxygen atmosphere improved the superconducting properties significantly.…”