Structural and antiferromagnetic characterization of noncollinear D019 Mn3Ge polycrystalline film

Distorted Heusler compound of D019 Mn3Ge polycrystalline films were studied in terms of their crystalline structures and antiferromagnetic behavior by varying annealing temperature and Mn-Ge composition. Although low temperature growth for 30 nm Mn3Ge showed no diffraction peaks in X-ray diffraction patterns, high temperature growth over 773 K with Mn-rich composition is found to promote the (0001) orientation of D019 Mn3Ge which resulted in the emergence of an exchange bias effect in Co0.6Fe0.4 ferromagnetic layer at 120 K. The exchange bias field of 12 Oe in Mn3.16Ge film grown at 773 K were improved to 61 Oe by enriching Mn composition to Mn3.97Ge. The average blocking temperature was measured to be at 150 K which is not as high as its reported Néel temperature of 390 K in the bulk state, however, further improvements are expected by doping additional transition elements.