2011-12-26Iron based superconducting wires |
Since the discovery of iron-based superconducting materials by Rotter, Tegel, and Johrendt [PRL, 101, 107006 (2008)] the search for potential applications of these new superconductors continues to intensify. One of the promising materials of this class is FeSe, which has a relatively low toxicity and the critical temperature, Tc, of the superconducting transition of about 8 K. The Tc of this compound increases up to 37 K at high pressure. Thus it should be possible to increase the Tc of this compound very significantly by preparing a thin film or a nanowire with high internal stress. Recently a Japanese group lead by Y. Takano achieved some success in this direction. They made quenched superconducting wires with Tc increased up to 10 K. The critical current density was also improved. To fabricate such wires a Fe tube was packed with Se powder and then was drawn down to the diameter of 1 mm. Such wires were sealed in a quartz tube under pure Ar atmosphere. Then the sample was annealed at 800°C for 2 hours. The quenching was done by removing the wires from the furnace and cooling them quickly at room temperature.
On the figure: Four different samples have been prepared and measured. The samples have been made by slow-heating and furnace-cooling (W1), rapid-heating and furnace-cooling (W2), slow-heating and quenching (W3), and rapid-heating and quenching (W4). The quenched sample W4 showed superior superconducting characteristics.
Iron based superconducting wires
