Credit: Image courtesy of C.L. Chien and the American Physical Society (modified by Claire Ballweg, Department of Energy)
Devices that take advantage of spin currents for their special electronic properties are made up of multiple layers of materials. For the measurements in this research, a device was made up of yttrium iron garnet (YIG) and a normal metal separated by an antiferromagnetic (AF – a material whose magnetic moments are canceled) insulating layer. (The heat sink and heater allowed a temperature gradient (T) for the spin current generation). The introduction of the AF insulating layer amplifies the spin current (blue curve in right figure) as compared to the plain metal-YIG interface (red curve) by up to a factor of 10. In the absence of the ferromagnetic YIG substrate, the spin current disappears (black line). The data in the figure was for a platinum (Pt) metal layer; the data correlate the applied field (H) with the measured inverse spin Hall voltage (V).