paper

Possible superconductivity above 25 K in single crystalline Co-doped BaFeAs

arXiv:0811.2621 · doi:10.1143/JPSJ.78.023702

Abstract

We present superconducting properties of single crystalline Ba(FeCo)As by measuring magnetization, resistivity, upper critical field, Hall coefficient, and magneto-optical images. The magnetization measurements reveal fish-tail hysteresis loop at high temperatures and relatively high critical current density above A/cm at low temperatures. Upper critical field determined by resistive transition is anisotropic with anisotropic parameter 3.5. Hall effect measurements indicate that Ba(FeCo)As is a multiband system and the mobility of electron is dominant. The magneto-optical imaging reveals prominent Bean-like penetration of vortices although there is a slight inhomogeneity in a sample. Moreover, we find a distinct superconductivity above 25 K, which leads us to speculate that higher transition temperature can be realized by fine tuning Co-doping level.

4 pages, 5 figures

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