Structural, magnetic and electronic properties of L21-ordered Ru2–xMn1+xAl Heusler alloy thin films

The cubic Heusler alloy Ru2–xMn1+xAl is grown in thin film form on MgO and MgAl2O4 substrates. It is a highly spin-polarised ferrimagnetic metal, with weak magnetocrystalline anisotropy. Although structurally and chemically similar to Mn2RuxGa, it does not exhibit ferrimagnetic compensation, or large magneto galvanic effects. The differences are attributed to a combination of atomic order and the hybridisation with the group 13 element Al or Ga. The spin polarisation is around 50% to 60%. There is a gap in the density of states just above the Fermi level in fully ordered compounds.