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.