Studium strukturních a magnetických vlastností Heuslerových slitin na bázi Mn

Abstract

Goal of this bachelor’s thesis is to study alloys based on Mn, specifically Mn2FeSi and Mn2FeAl alloys, which have potential for applications in modern technologies like spintronics. These samples were prepared by the method of induction melting and part of them was annealed for 100 hours to achieve better homogeneity in terms of element distribution. Scanning electron microscope, X-ray diffractometer and vibrating sample magnetometer have been used for characterisation of structural and magnetic properties of studied alloys. Obtained data show that Mn2FeSi alloy has multiple phases before and also after annealing. Diffractograms of these alloys indicate presence of XA or L21 structure typical for Heusler alloys. Magnetic measurements show that Mn2FeSi is paramagnetic at room temperature and antiferromagnetic at temperature close to 0 K. There are also signs of ferromagnetism or ferrimagnetism between para- and antiferromagnetic state. The Mn2FeAl sample is single phase alloy regardless of annealing. The structure of Heusler alloys was not confirmed by X-ray diffraction. There is cubic β-Mn structure likely to be formed. Samples of Mn2FeAl are paramagnetic at room temperature and their negative Curie temperature unequivocally point to presence of antiferromagnetic state at temperature close to 0 K.