Evidence for Magnetic (AF SDW) 2D-Phase Transition in Doped Ferropnictides and Ferroselenides

摘要

The evidence for magnetic (AF SDW) 2D phase transition preceding a superconducting one (T_c < T_m) is presented for the plane of the FeAs(Se) layers of doped ferropnictides (-selenides). In contrast to the parent undoped compounds, the incommensurability of SDW and the lattice period leads to the formation of CDW with one-half wavelength. The magnetic phase (H-T) diagram of doped ferropnictides (-selenides) is characteristic of systems in which dielectric (e-h) and superconducting (e-e) pairings coexist.