Publications (3)9.91 Total impact
-
Article: Superconducting phases in potassium-intercalated iron selenides.
[show abstract] [hide abstract]
ABSTRACT: The ubiquitous coexistence of majority insulating 245 phases and minority superconducting (SC) phases in A(x)Fe(2-y)Se(2) (A = K, Cs, Rb, Tl/Rb, Tl/K) formed by high-temperature routes makes pure SC phases highly desirable for studying the intrinsic properties of this SC family. Here we report that there are at least two pure SC phases, K(x)Fe(2)Se(2)(NH(3))(y) (x ≈ 0.3 and 0.6), determined mainly by potassium concentration in the K-intercalated iron selenides formed via the liquid ammonia route. K(0.3)Fe(2)Se(2)(NH(3))(0.47) corresponds to the 44 K phase with lattice constant c = 15.56(1) Å and K(0.6)Fe(2)Se(2)(NH(3))(0.37) to the 30 K phase with c = 14.84(1) Å. With higher potassium doping, the 44 K phase can be converted into the 30 K phase. NH(3) has little, if any, effect on superconductivity. Thus, the conclusions should apply to both K(0.3)Fe(2)Se(2) and K(0.6)Fe(2)Se(2) SC phases. K(0.3)Fe(2)Se(2)(NH(3))(0.47) and K(0.6)Fe(2)Se(2)(NH(3))(0.37) stand out among known superconductors as their structures are stable only at particular potassium doping levels, and hence the variation of T(c) with doping is not dome-like.Journal of the American Chemical Society 02/2013; 135(8):2951-4. · 9.91 Impact Factor -
Article: Superconductivity on the verge of Mott localization in ternary iron sulfide
[show abstract] [hide abstract]
ABSTRACT: We report the results of electrical and magnetic properties on two new compounds, K0.8Fe1.7S2 and K0.8Fe1.7SeS, both having similar structures to newly discovered superconducting K0.8Fe1.7Se2. K0.8Fe1.7S2 exhibits a semiconductor-like electrical property and undergoes an anti-ferromagnetic transition at about 260 K. Upon replacing half of S with Se, K0.8Fe1.7SSe becomes a superconductor at 25 K, implying the superconductivity evolves from a Mott AFM state in Fe-Se based superconductors.02/2011; -
Article: Quenching of superconductivity by Co doping in K0.8Fe2Se2
[show abstract] [hide abstract]
ABSTRACT: We synthesized a series of K0.8Fe2-xCoxSe2 samples with nominal compositions 0\leq x\leq 0.035 and investigated their physical properties. The results show that the superconductivity in K0.8Fe2-xCoxSe2 is quenched down to 5 K by 0.5 at. % Co doping, the fastest quenching rate ever-reported. The role played here by Co is in contrast with the one in FeAs based superconductors where Co usually induces superconductivity from parent compounds. Such a rapid quenching favors a localized 3d model against the itinerant one for iron pnictide superconductors.02/2011;