Magnetic order and magneto-transport in half-metallic ferrimagnetic Mn${}_y$Ru${}_x$Ga thin films

Abstract

The ruthenium content of half-metallic Mn${}_2$Ru${}_x$Ga thin films, with a biaxially-strained inverse Heusler structure, controls the ferrimagnetism that determines their magnetic and electronic properties. An extensive study of Mn${}_y$Ru${}_x$Ga films on MgO (100) substrates with $1.8\le y\le 2.6$ and $x=0.5$, 0.7 or 0.9, including crystallographic, magnetic order, magneto-transport and spin polarisation is undertaken to map specific composition-dependent properties in this versatile ternary system. A comparison of experimental densities obtained from X-ray reflectivity with calculated densities indicates full site occupancy for all compositions, which implies chemical disorder. All moments lie on the Slater-Pauling plot with slope 1 and all except $x=0.5$, $y=2.2$ exhibit magnetic compensation at \tcmp~below 500~K. The coercivity near \tcmp~exceeds 10~T. Increasing the Mn or Ru content raises \tcmp, but increasing Ru also decreases the spin polarisation determined by point contact Andreev reflection. Molecular field theory is used to model the temperature dependence of the net ferrimagnetic moment and three principal exchange coefficients are deduced. Marked differences in the shape of anomalous Hall and net magnetisation hysteresis loops are explained by substantial canting of the small net moment by up to \SI{40}{\degree} relative to the $c$-axis in zero field, which is a result of slight non-collinearity of the Mn${}^{4c}$ sublattice moments due to competing intra-sublattice exchange interactions arising from antisite disorder and excess Mn in the unit cell. Consequences are reduced spin polarisation and an enhanced intrinsic contribution to the anomalous Hall effect. The systematic investigation of the physical properties as a function of $x$ and $y$ will guide the selection of compositions to meet the requirements for magnonic and spintronic MRG-based devices.

References in corpus (7)

• Large Noncollinearity and Spin Reorientation in the Novel Mn2RhSn Heusler Magnet
• Single pulse all-optical toggle switching of magnetization without Gd: The example of Mn2RuxGa
• Large Spin Anomalous Hall Effect in L1${}_0$-FePt: Symmetry and Magnetization Switching
• Ultra-fast Double Pulse All-Optical Re-switching of a Ferrimagnet
• Magnetization dynamics of the compensated ferrimagnet $M{n}_{2}R{u}_{x}Ga$
• Imaging Domains in a Zero-Moment Half Metal
• Magnetic reversal and pinning in a perpendicular zero moment half-metal

Cited by in corpus (4)

• Two-dimensional fully-compensated Ferrimagnetism
• First-principles insights into all-optical spin switching in the half-metallic Heusler ferrimagnet Mn${}_2$RuGa
• Quasi-static magnetization dynamics in a compensated ferrimagnetic half-metal -- Mn${}_2$Ru${}_x$Ga
• Electric-Field-induced Two-Dimensional Fully Compensated Ferrimagnetism and Emergent Transport Phenomena