Strukturní a fyzikální vlastnosti slitin Mn2FeSn

Abstract

Analysis of the Mn2FeSn alloy, which could be used in modern technologies such as spintronics, has been carried out within this thesis. Samples were prepared using three different methods – die casting, arc melting and melt spinning. Subsequently part of them was annealed at 500 °C for 100 hours. Based on the results of X-ray diffractometer measurements, scanning electron microscope measurements and positron annihilation spectroscopy the characterisation of structure, phases and defects of crystal lattice has been performed. Magnetic properties have been investigated using vibrating sample magnetometer and magnetic properties measurement system. In spite of theoretical prediction for the Mn2FeSn alloy to have the Heusler alloy structure, results indicate the presence of dominant hexagonal Ni3Sn type of structure. The occurrence of three or more phases for each sample has been observed. Dominance of Sn vacancies is indicated by the results of positron lifetime spectroscopy. In terms of magnetism the Mn2FeSn alloy is ferromagnetic at room temperature. Hysteresis loop evinces asymmetrical behaviour at low temperatures close to 10 K caused by an exchange bias, which probably originates from interaction between ferromagnetic phase and antiferromagnetic or ferrimagnetic phase.