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In this contribution, I will present the important aspects of crystal growth and the influence of chemical substitution in Fe based superconductors. High temperature solution growth technique is one of most powerful and widely used technique to grow single crystals of various materials. Solution growth technique has the potential to control high vapour pressures, given the fact that, in Fe-based superconductors elements with high vapour pressure like As, K, Li and Na have to be handled during the crystal growth procedure. In this scenario high temperature solution growth is the best suitable growth technique to synthesize sizable homogeneous single crystals. Using self-flux high temperature solution growth technique, large centimeter-sized high quality single crystals of BaFe2As2 were grown. This pristine compound BaFe2As2 undergoes structural and magnetic transition at 137 K. By suppressing this magnetic ordering and stabilizing tetragonal phase with chemical substitution, like Co-doping and Na-doping, bulk superconductivity is achieved. Superconducting transitions of as high as Tc = 34 K [1] with Na substitution and Tc = 25 K [2] with Co-doping were obtained. Angle resolved photoemission spectroscopy was performed on all Ba1-xNaxFe2As2 crystals. The Fermi surface of hole-doped Ba1-xNaxFe2As2 is to a large extent the same as the Fermi surface found for the K-doped sister compounds, suggesting a similar impact of the substitution of Ba by either K or Na on the electronic band dispersion at the Fermi level. A combined electronic phase diagram has been achieved for both electron doping with Co and hole doping with Na in BaFe2As2. [1] S. Aswartham et.al., Physical Review B 85, 224520 (2012). [2] S. Aswartham et.al., Journal of Crystal Growth 314 (2011) 341-348. |
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