  Efficient detection of the magnetic state at nanoscale dimensions is an
important step to utilize spin logic devices for computing. Magnetoresistance
effects have been hitherto used in magnetic state detection, but they suffer
from energetically unfavorable scaling and do not generate an electromotive
force that can be used to drive a circuit element for logic device
applications. Here, we experimentally show that a favorable miniaturization law
is possible via the use of spin-Hall detection of the in-plane magnetic state
of a magnet. This scaling law allows us to obtain a giant signal by spin Hall
effect in CoFe/Pt nanostructures and quantify an effective spin-to-charge
conversion rate for the CoFe/Pt system. The spin-to-charge conversion can be
described as a current source with an internal resistance, i.e., it generates
an electromotive force that can be used to drive computing circuits. We predict
that the spin-orbit detection of magnetic states can reach high efficiency at
reduced dimensions, paving the way for scalable spin-orbit logic devices and
memories.
