Ferrimagnetism and disorder of epitaxial Mn2xCoxVAl Heusler compound thin films

Markus Meinert (1) , Jan-Michael Schmalhorst (1) , Günter Reiss (1) , Elke Arenholz (2)

1 Department of Physics
2 ALS - Advanced Light Source [LBNL Berkeley]

The quaternary full Heusler compound Mn 2−x Co x VAl with x = 1 is predicted to be a half-metallic antiferromagnet. Thin films of the quaternary compounds with x = 0... 2 were prepared by DC and RF magnetron co-sputtering on heated MgO (001) substrates. The magnetic structure was examined by x-ray magnetic circular dichroism and the chemical disorder was characterized by x-ray diffraction. Ferrimagnetic coupling of V to Mn was observed for Mn 2 VAl (x = 0). For x = 0.5, we also found ferrimagnetic order with V and Co antiparallel to Mn. The observed reduced magnetic moments are interpreted with the help of band structure calculations in the coherent potential approximation. Mn 2 VAl is very sensitive to disorder involving Mn, because nearest-neighbor Mn atoms couple antiferromagnetically . Co 2 VAl has B2 order and has reduced magnetization. In the cases with x ≥ 0.9 conventional ferromagnetism was observed, closely related to the atomic disorder in these compounds.

Mots clés: Physical Sciences

Markus Meinert, Jan-Michael Schmalhorst, Günter Reiss, Elke Arenholz. Ferrimagnetism and disorder of epitaxial Mn2xCoxVAl Heusler compound thin films. Journal of Physics D: Applied Physics, 2011, 44 (21), pp.215003. ⟨10.1088/0022-3727/44/21/215003⟩. ⟨hal-00618208⟩