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Micro magnet location using spin waves

In this work, we present experimental data demonstrating the feasibility of magnetic object location using spin waves. The test structure includes a Y$_3$Fe$_2$(FeO$_4$)$_3$) (YIG) film with four micro-antennas placed on the edges. A constant in-plane bias magnetic field is provided by NdFeB permanent magnet. Two antennas are used for spin wave excitation while the other two are used for the inductive voltage measurement. There are nine selected places for the magnet on the film. The magnet was subsequently placed in all nine positions and spin wave transmission and reflection were measured. The obtained experimental data show the difference in the output signal amplitude depending on the magnet position. All nine locations can be identified by the frequency and the amplitude of the absolute minimum in the output power. All experiments are accomplished at room temperature. Potentially, spin waves can be utilized for remote magnetic bit read-out. The disadvantages and physical constraints of this approach are also discussed.