Magnetoresistive detection of spin waves

We explore a detection method for spin-waves that consists of integrating
a magneto-resistive sensor on a magnonic waveguide. When subjected to the
stray magnetic field generated by the spin-wave, the relative orientation
of the magnetizations of the two magnetic layers in the sensor oscillates
in time, resulting in an electrical resistance change according to the
so-called giant magneto-resistance effect. Upon application of an
appropriate current bias, this variation of resistance translates into a
sizable microwave voltage. At the sub-micrometer scale explored here, this
signal is about fifty times larger than the one extracted from
conventional inductive measurements of spin-waves for comparable detection
areas. Moreover, such a detection scheme is expected to scale very
favorably down to the nanometer size relevant for future magnon-based data
processing architectures.