Epitaxial Growth of Hard Ferrimagnetic Mn3Ge Film on Rhodium Buffer Layer

Abstract

Mn 3 Ge has a tetragonal Heusler-like D0 22 crystal structure, exhibiting a large uniaxial magnetic anisotropy and small saturation magnetization due to its ferrimagnetic spin structure; thus, it is a hard ferrimagnet. In this report, epitaxial growth of a Mn 3 Ge film on a Rh buffer layer was investigated for comparison with that of a film on a Cr buffer layer in terms of the lattice mismatch between Mn 3 Ge and the buffer layer. The film grown on Rh had much better crystalline quality than that grown on Cr, which can be attributed to the small lattice mismatch. Epitaxial films of Mn 3 Ge on Rh show somewhat small coercivity (H c = 12.6 kOe) and a large perpendicular magnetic anisotropy (K u = 11.6 Merg/cm 3 ), comparable to that of the film grown on Cr.

Structural and Magnetic Properties of Mn3Ge Grown on a Thin Polycrystalline MgO Seed Layer

“…The saturation magnetization ( M s ) is around 175 kA m −1 , which is close to the theoretical value (183 kA m −1 ) . Both M s and are in agreement with literature values . Its cannot to be estimated by measuring the in‐plane saturation field, because its effective anisotropy field is beyond the available magnetic field.…”

“…The epitaxially‐grown D 0 22 ‐Mn 3 Ge shows very low M s (70–130 kA m −1 ) due to the ferrimagnetic configuration between Mn atoms in the D 0 22 structure . Meanwhile, this tetragonal D 0 22 structure induces a Jahn‐Teller effect, which leads to high PMA in D 0 22 ‐Mn 3 Ge ( up to 1.2 MJ m −3 ) . Theoretical calculations also indicate low α and 100% , i.e., half‐metallicity .…”

“…Up to now, D 0 22 ‐Mn 3 Ge is typically deposited on single crystal (sc) MgO substrates by molecular beam epitaxy (MBE) for studying the structural and magnetic properties. Different deposition conditions and procedures are screened in MBE for the sake of low surface roughness, high PMA, and annealing stability . However, for the integration of D 0 22 ‐Mn 3 Ge into MTJ stacks in industrial applications, sc‐MgO substrates cannot be used.…”

“…[14][15][16][17] Meanwhile, this tetragonal D0 22 structure induces a Jahn-Teller effect, which leads to high PMA in D0 22 -Mn 3 Ge (K eff U up to 1.2 MJ m À3 ). [17][18][19] Theoretical calculations also indicate low α and 100% η, i.e., half-metallicity. [15,20] All properties shown in D0 22 -Mn 3 Ge make it a good candidate for both FL and RL applications in p-MTJs.…”

Manganese-based Permanent Magnets

“…Interestingly, their results suggest that doping the interstitial sites of MnBi with an interstitial can increase the saturation magnetization. The final paper by Sugihara et al [5] focuses on the behavior of Mn3Ge thin films, which exhibit a tetragonal Heusler-like D022 crystal structure.…”