Abstract
The crystal structure, magnetism properties, and density of states for FeAs layered compound SrFe 2As 2 have been investigated by using the density functional theory (DFT) method. The magnetism under a checkerboard nearest neighbor anti-ferromagnetic (NN AFM) and ferromagnetic (FM) order ground-state have been analyzed with substitution for Sr with K ion in Sr 1− x K x Fe 2As 2. The results indicate that the distortion of FeAs tetrahedrons is sensitive to the electron doping concentration. The system magnetism was suppressed by K doping in NN-AFM ground state instead of FM. The density of states at Fermi level N ( E F ) under NN AFM ground state would be regarded as a driving force for the increased T c of Sr 1− x K x Fe 2As 2 system as observed experimentally. Our calculation reflects that NN AFM type spin fluctuation may still exist in the Sr 1− x K x Fe 2As 2 system and it may be an origin of strong spin fluctuation in this system besides the spin density wave (SDW) states.
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