Investigation of the quaternary Fe_{2 - X}Co_xMnSi (0 ≤ x ≤ 0.6) alloys by structural, magnetic, resistivity and spin polarization measurements

A detailed study of the Fe_{2 - x}Co_xMnSi (0 ≤ x ≤ 0.6) alloys has been carried out by investigating the samples by x-ray diffraction, Mössbauer spectroscopy, magnetization, transport and current spin polarization measurements. A perfectly ordered L2₁ phase is found to exist for x = 0.4. Competing magnetic interactions between ferromagnetic and antiferromagnetic (AFM) phases are seen in the alloys with x < 0.2, whereas the AFM phase is completely absent for x ≥ 0.2 as revealed by the magnetization and resistivity data. The Curie temperature and saturation magnetization values increase with increase in the Co concentration. Anomalous, non metallic-like behaviour is observed for x = 0.4. Current spin polarization values of 0.61 ± 0.01 and 0.66 ± 0.01 were deduced for x = 0.2 and x = 0.4 respectively, using the point contact Andreev reflection spectroscopy . Considering the high spin polarization and Curie temperature, materials with x ≥ 0.2 appear to be very promising for spintronic devices.