  Parameters of the energy gap and, consequently, electronic, magnetic and
galvanomagnetic properties in different X$_2$YZ Heusler alloys can vary quite
strongly. In particular, half-metallic ferromagnets (HMFs) and spin gapless
semiconductors (SGSs) with almost 100% spin polarization of charge carriers are
promising materials for spintronics. The changes in the electrical, magnetic
and galvanomagnetic properties of the Co$_2$YSi (Y = Ti, V, Cr, Mn, Fe) and
Co$_2$MnZ Heusler alloys (Z = Al, Si, Ga, Ge) in possible HMF and/or SGS states
were followed and their interconnection was established. Significant changes in
the values of the magnetization and residual resistivity were found. At the
same time, the correlations between the changes in these electronic and
magnetic characteristics depending on the number of valence electrons and spin
polarization are observed.

Materials Science