Synthesis and Physical Properties of the New Potassium Iron Selenide Superconductor K0.80Fe1.76Se2

TitleSynthesis and Physical Properties of the New Potassium Iron Selenide Superconductor K0.80Fe1.76Se2
Publication TypeBook
Year of Publication2013
AuthorsHu R, Mun ED, Ryan DH, Cho K, Kim H, Hodovanets H, Straszheim WE, Tanatar MA, Prozorov R, Rowan-Weetaluktuk WN, Cadogan JM, Altarawneh MM, Mielke CH, Zapf VS, Bud'ko SL, Canfield PC
Series EditorWang NL, Hosono H, Dai P
Series TitleIron-Based Superconductors: Materials, Properties, and Mechanisms
PublisherPan Stanford Publishing Pte Ltd
ISBN Number978-981-4303-23-1978-981-4303-22-4
Accession NumberWOS:000328223400003
Keywordsanisotropy, fe7se8, high-field superconductors, MAGNETIC PHASE-DIAGRAM, MOSSBAUER, penetration depth, pressure, single-crystals, spectroscopy, temperature

In this chapter, we review our studies of the K0.80Fe1.76Se2 superconductor, with an attempt to elucidate the crystal growth details and basic physical properties over a wide range of temperatures and applied magnetic field, including anisotropic magnetic and electrical transport properties, thermodynamic, London penetration depth, magneto-optical imaging and Mossbauer measurements. We find that: (i) Single crystals of similar stoichiometry can be grown both by furnace-cooled and decanted methods; (ii) Single crystalline K0.80Fe1.76Se2 shows moderate anisotropy in both magnetic susceptibility and electrical resistivity and a small modulation of stoichiometry of the crystal, which gives rise to broadened transitions; (iii) The upper critical field, Hc(2)(T) is degrees similar to 55 T at 2 K for H similar to c, manifesting a temperature dependent anisotropy that peaks near 3.6 at 27 K and drops to 2.5 by 18 K; (iv) Mossbauer measurements reveal that the iron sublattice in K0.80Fe1.76Se2 clearly exhibits magnetic order, probably of the first order, from well below T-c to its Neel temperature of TN = 532 similar to 2 K. It is very important to note that, although, at first glance there is an apparent dilemma posed by these data: high T c superconductivity in a near insulating, large ordered moment material, analysis indicates that the sample may well consist of two phases with the minority superconducting phase (that does not exhibit magnetic order) being finely distributed, but connected with in an antiferromagnetic, poorly conducting, matrix, essentially making a superconducting aerogel.

URL<Go to ISI>://WOS:000328223400003