Spin Hall Effects in Metallic Antiferromagnets

We investigate four CuAu-I-type metallic antiferromagnets for their potential as spin current detectors using spin pumping and inverse spin Hall effect. Nontrivial spin Hall effects were observed for FeMn, PdMn, and IrMn while a much higher effect was obtained for PtMn. Using thickness-dependent measurements, we determined the spin diffusion lengths of these materials to be short, on the order of 1 nm. The estimated spin Hall angles of the four materials follow the relationship $\mathrm{PtMn}>\mathrm{IrMn}>\mathrm{PdMn}>\mathrm{FeMn}$, highlighting the correlation between the spin-orbit coupling of nonmagnetic species and the magnitude of the spin Hall effect in their antiferromagnetic alloys. These experiments are compared with first-principles calculations. Engineering the properties of the antiferromagnets as well as their interfaces can pave the way for manipulation of the spin dependent transport properties in antiferromagnet-based spintronics.

Figure 1

A sketch illustrating the chemical structure of CuAu-I-type AFs ($X=\mathrm{Fe}$, Pd, Ir, Pt) and the spin pumping and spin Hall effect experiment for the Py/Cu/AF structures.

Figure 2

AMR-ISHE spectra measured at 9 GHz of the Py(15)/Cu(4)/AF(5) structure for FeMn, PdMn, IrMn, and PtMn at RT.

Figure 3

Thickness dependence of the weight $W_{\mathrm{ISHE}}$ of the symmetric component and estimation of the spin diffusion length for FeMn, PdMn, IrMn, and PtMn at RT.

Figure 4

(a) Frequency dependence of the linewidth broadening for the IrMn set of samples, and (b) the extraction of the damping enhancement with respect to pure Py at RT and 10 K.