Tilted spin current generated by the collinear antiferromagnet ruthenium dioxide

Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. It also influences how these spin currents generate spin-transfer torques in magnetic devices. Here we show that an out-of-plane damping-like torque can be generated in ruthenium dioxide (RuO2)/permalloy devices when the Neel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane. By measuring characteristic changes in all three components of the electric-field-induced torque vector as a function of the angle of the electric field relative to the crystal axes, we find that the RuO2 generates a spin current with a well-defined tilted spin orientation that is approximately parallel to the Neel vector. A maximum out-of-plane damping-like spin torque efficiency per unit electric field of 7 +/- 1 x 10(3) omega(-1) m(-1) is measured at room temperature. The observed angular dependence indicates that this is an antiferromagnetic spin Hall effect with symmetries that are distinct from other mechanisms of spin-current generation reported in antiferromagnetic and ferromagnetic materials. The collinear antiferromagnet ruthenium dioxide (RuO2) can generate an electric-field-induced spin current with a well-defined tilted spin orientation that is approximately parallel to the Neel vector.

Automated summary

Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. In this study, an out-of-plane damping-like torque is shown to be generated in RuO2/permalloy devices when the Neel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane. By measuring characteristic changes in the electric-field-induced torque vector, it is found that RuO2 generates a spin current with a well-defined tilted spin orientation parallel to the Neel vector. This antiferromagnetic spin Hall effect has distinct symmetries from other mechanisms of spin-current generation reported in antiferromagnetic and ferromagnetic materials.