Temperature-Driven Changes of Electronic Structure Through the Phase Transition in Magnetocaloric Compound Mn1.1Fe0.9P0.55As0.45

The electronic structure of magnetocaloric compound Mn
_1.1
Fe
_0.9
P
_0.55
As
_0.45
, prepared via solid-state sintering was studied. Adiabatic temperature change of 3.6 K was observed through the phase transition found at 273 K. The X-ray diffraction and time-of-flight secondary ion mass spectroscopy were applied to verify the purity and homogeneity of the sample. The X-ray photoemission spectroscopy was used to study electronic structure at room temperature and below the phase transition at 180 K. The existence of local magnetic moment was deduced from the exchange splitting effect found for 2p states of manganese. This effect was also studied below the phase transition at low temperature. It was reflected in the shape of the valence band. A shift of 0.15 eV was detected on the onset of the valence band at low temperature. The splitting of the 3s core lines of manganese and iron were investigated. The values of these splitting were obtained. No influence of phase transition was found on the photoemission spectra from iron 2p, phosphorus 2p, and arsenic 3d states.