Exploring the phase diagram of Fe-pnitides AFe₂As₂

Jun Sung Kim, POSTECH

High-Tc iron-pnictides, AFe₂As₂ (A = Ca, Sr, Ba, and Eu) have a layered structure consisting of metallic FeAs planes intercalated by alkaline earths. Here we present recent investigations on single crystals of undoped and Fe-site doped AFe₂As₂. The parent undoped compound has an antiferromagnetic spin-density-wave ground state, which can be suppressed by changing the alkaline earths at the A-sites or the substitution of Co/Mn/Ru at the Fe-sites. Superconducting state is induced by Co subsitition or isovalent Ru- subsititution, while no superconductivity is observed upon Mn subsitition at the Fe sites. The magnetic and superconducting phase diagram will be presented and discussed in terms of the inter-band nesting effect and its possible influence on the high-T_c superconductivity.