Theoretical consideration of magnetic phase formation in MnFeAsyP1−y and Mn2−x FexAs0.5P0.5 systems in the collective electron model

Abstract

Experimental magnetic field dependences of magnetization in isostructural systems MnFeAsyP1−y (0.2 ≤ у ≤ 0.66) and Mn2−xFexAs0.5P0.5 (0.5 ≤ x ≤ 1.1) are analyzed by using the results of calculations from the first principles and the model approach. It is shown that the basis of the electronic mechanism of changing the type of magnetic phases in the system Mn2−xFexAs0.5P0.5 with cationic substitution is the change in the filling of the d-band. In the system MnFeAsyP1−y with anionic substitution the destabilization of the ferromagnetic phase and the occurrence of an antiferromagnetic one with decreasing the arsenic concentration can be caused by a change of the width of density of electronic states, owing to a considerable reduction of the unit-cell volume.