Congratulations to third year PGR David Newman, whose paper ‘Electrical Detection of DC Spin Current Propagation Through an Epitaxial Antiferromagnetic NiO Layer’ has recently been published in IEEE Transactions on Magnetics.
David explains this work and the impact of its findings:
Spin currents (net transfer of spin angular momentum) have been suggested as potential successors to charge currents in areas like magnetic data storage. A spin current can be generated by a mechanism known as ‘spin pumping’ whereby a ferromagnetic (FM) layer is excited into resonance and then ‘pumps’ a spin current into an adjacent nonmagnetic (NM) layer. Recently, work has even found that antiferromagnetic (AFM) layers could even be used to amplify the amount of spin current produced.
The main issue comes with the difficulty in observing a pure spin current. Current techniques mainly consist of detecting the spin transfer torque exerted on an additional FM layer (AC spin current). Alternatively, the DC spin current can be observed by the transverse charge current generated by a spin current propagating through a heavy metal (like Pt) via the inverse spin Hall effect (ISHE).
In our work, we measure the ISHE on a sample with an AFM layer where the AC spin current has already been detected (see separate publication: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.217201) and, with some experimental considerations, extract the DC spin current. By showing AC and DC spin current components can be observed in the same sample, this work provides the pathway to a more complete perspective of spin current propagation through an AFM layer which is important in the development of spintronic technologies in areas such as magnetic data storage.