Fermi Level Engineering of Mn2RuxGa Thin Films

Mn
₂
Ru
_x
Ga (MRG) is a fully compensated half-metallic ferrimagnet [1]. We aim to engineer the position of the Fermi level in MRG thin films to modify the spin polarisation. Previous investigations of magnetoresistance of MRG indicate that the Fermi level is positioned below the middle of the gap [1]. DFT calculations show that Mn
^4a
-Ga
^4b
antisites provide ~ 1 electron/antisite thereby increasing the electronic pressure in Mn
₂
Ru
_x
Ga thin films and raising the Fermi level [2]. To investigate this effect, Mn-deficient and Mn-rich MRG films with varying Ru content, were prepared by magnetron sputtering. The structural properties of the films were investigated using X-ray diffraction spectroscopy and X-ray reflectometry. The electronic and magnetic properties were investigated using the Anomalous Hall effect and the Van der Pauw method. Our results show that the Mn
^4c
occupancy can be controlled. Films with low Ru content show an increase in Hall angle up to 2% in Mn-rich films. These films can be expected to have high spin polarization which can be verified using point contact Andreev reflection (PCAR) measurements.