Magnetic moments and exchange splitting in Mn3s and Mn2p core levels of magnetocaloric Mn1.1Fe0.9P0.6As0.4 and Mn1.1Fe0.9P0.5As0.4Si0.1 compounds

摘要

The magnetocaloric Mn1.1Fe0.9P0.6As0.4 and Mn1.1Fe0.9P0.5As0.4Si0.1 compounds were prepared via spark plasma sintering method. Prepared structural studies including X-ray diffraction measurements have shown the unit cell expanding for silicon substituted sample. The silicon substitution leads also to increase of the adiabatic temperature change from 2.4 K to 3.7 K through the phase transition at 258 K and 268 K in comparison to Mn1.1Fe0.9P0.6As0.4. The magnetic entropy curve showed a complex structure at the field of 5 T. The total saturation of magnetic moments derived from magnetic measurements corresponded to 3.9 mu B/f.u. at low temperature. The electronic structure was tested by X-ray photoemission spectroscopy at room temperature and below the phase transition at 180 K. The observed exchange splitting of 2p states of manganese indicated existence of magnetic moments of d electrons and correlate with changes in the valence band measurements. The specific magnetic moments of iron and manganese were deduced from the obtained values of splitting within the 3s levels.