Structure and magnetism in metastable bcc Co1−xMnx epitaxial films

From Binary to Ternary Transition-Metal Nitrides: A Boost toward Nitrogen Magneto-Ionics

“…, the first 150 s), M S subsequently levels off for CoN films but continues to increase in CoMnN films before reaching a stable value for times close to 1500 s. As a result, a 6.7-fold enhancement in the obtained steady-state value of M S is achieved in voltage-actuated CoMnN compared to CoN, from 102 to 672 emu cm –3 , respectively (in agreement with the magnetic hysteresis loops shown in Figure S3b,c). Note that, as reported earlier, , M S for CoMn is slightly larger than for pure Co (Figure S3d), but this fact by itself alone cannot explain the obvious magneto-ionic enhancement of M S observed in their nitrides and demonstrates that Mn-substitution boosts magneto-ionics by some other mechanisms, for example, the dissimilar resistivity variations during the denitrification processes in CoN and CoMnN films. With the goal to investigate the eventual influence of the growing method and to be able to compare with previously reported results, 85 nm thick CoN and CoMnN films were also grown by triode sputtering.…”

“…Also, Mn-substitution could introduce more defects in the crystal lattice and increase electrical resistivity, possibly leading to the modification of electrical properties, from metallic-like to semi-metallic or semiconducting behavior . Incorporation of Mn may trigger hopping mechanisms and hence change the transport properties, as studied in earlier cobalt ferrite systems. , Most importantly, the enhancement of saturation magnetization and perpendicular magnetic anisotropy of host FM target materials with moderate Mn introduction has also been confirmed both from experimental and theoretical studies. − Therefore, introducing Mn into FM nitrides ( e.g. , CoN) might result in synergetic effects and could make magneto-ionics more attractive for spin-based and other magnetoelectric devices.…”

Tracing magnetic atom diffusion with annealing at the interface between CoMn alloy and MnGa layer by X-ray magnetic circular dichroism

“…At the as-grown stage, XMCD line shapes of Co L-edge are similar to those of CoMn [18]. The Mn L-edge XMCD is composed of both CoMn and MnGa.…”

“…Other candidates for the magnetic switching layer combined with Mn3δ Ga are the metastable body-centered-cubic (bcc) (Co,Mn)-based alloy which exhibits high TMR ratio and is compatible to the MgO insulating barrier layer [15][16][17][18]. In particular, perpendicular magnetization switching using Mn-based alloys is strongly demanded for high TMR spintronic devices [19].…”

“…Figure 1 shows the wide-range XAS in (µ + +µ -)/2 including Mn and Co L-edges for CoMn/MnGa with annealing temperature dependence and the reference spectrum of bcc CoMn film. The spectra were normalized at the Co L3-edge peak intensity to be 1 in order to deduce the intensity ratio between Mn and Co. For the 30-nm-thick CoMn film without MnGa as a reference [18], the intensity ratio of Mn to Co is estimated to be 0.55 from the spectral intensity in Fig. 1.…”