Spin transport through the metallic antiferromagnet FeMn

We investigate spin transport through metallic antiferromagnets using measurements based on spin pumping combined with inverse spin Hall effects in $\mathrm{N}{\mathrm{i}}_{80}\mathrm{F}{\mathrm{e}}_{20}/\mathrm{FeMn}/\mathrm{W}$ trilayers. The relatively large magnitude and opposite sign of spin Hall effects in W compared to FeMn enable an unambiguous detection of spin currents transmitted through the entire FeMn layer thickness. Using this approach we can detect two distinctively different spin transport regimes, which we associate with electronic and magnonic spin currents, respectively. The latter can extend to relatively large distances (≈9 nm) and is enhanced when the antiferromagnetic ordering temperature is close to the measurement temperature.

Figure 1

(a) Schematic diagram of the device with coplanar waveguide. (b) Schematic of spin pumping and the inverse spin Hall effect measurement on Py/FeMn/W trilayers.

Figure 2

Anisotropic magnetoresistance–inverse spin Hall effect spectra measured at 4 GHz for Py(12)/$\text{FeMn}\left(t\right)$/W(4) structures at room temperature for four different thicknesses $t$ of the FeMn layer; (a) 0, (b) 4, (c) 8, and (d) 10 nm. Green and blue lines indicate the ISHE and AMR contributions to the combined fit shown in red. Black symbols represent experimental data.

Figure 3

Thickness dependence of the relative spin Hall effect contribution to the total voltage $W_{ISHE}$ measured at room temperature for frequencies from 4 to 9 GHz.

Figure 4

(a) FeMn thickness $t$ dependence of the resonance linewidth Δ$H$ measured at frequencies 4–9 GHz. (b) FeMn thickness $t$ dependence of the resonance field $H_{\mathrm{res}}$ measured at frequencies 4–9 GHz.