Possible Superconductivity above 25 K in Single-Crystalline Co-Doped BaFe<SUB>2</SUB>As<SUB>2</SUB>
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We present the superconducting properties of single-crystalline Ba(Fe<SUB>0.9</SUB>Co<SUB>0.1</SUB>)<SUB>2</SUB>As<SUB>2</SUB> by measuring its magnetization, resistivity, upper critical field, Hall coefficient, and magneto-optical images. The magnetization measurements reveal a fish-tail hysteresis loop at high temperatures and a relatively high critical current density above <I>J</I><SUB>c</SUB>=10<SUP>5</SUP> A/cm<SUP>2</SUP> at low temperatures. The upper critical field determined by resistive transition is anisotropic with an anisotropic parameter of ∼3.5. Hall effect measurements indicate that Ba(Fe<SUB>0.9</SUB>Co<SUB>0.1</SUB>)<SUB>2</SUB>As<SUB>2</SUB> is a multiband system and that the mobility of electrons is dominant. Magneto-optical imaging reveals a prominent Bean-like penetration of vortices, although there is a slight inhomogeneity in a sample. Moreover, we observe distinct superconductivity above 25 K, which leads us to speculate that a higher transition temperature can be realized by fine-tuning the Co-doping level.
- Journal of the Physical Society of Japan
Journal of the Physical Society of Japan 78(2), 023702-023702, 2009
THE PHYSICAL SOCIETY OF JAPAN