Magnetic field detection with single mode spin wave interference in asymmetric structure

The magnetic field detection based on the interference phenomenon of surface-mode spin waves has been demonstrated in yttrium iron garnet (YIG) thin films, where the asymmetric arrangement of two excitation sources and one detection antenna allows for the field detection with a simple YIG strip structure that does not require microfabrication. The magnetic field can be detected by observing changes in the amplitude of the standing wave at the detection position, which result from alterations in the wavenumber of the excited spin wave caused by variations in the magnetic field. Time-domain measurements confirmed that the interference signal of the spin wave changed with the magnetic field. The induced electromotive force yielded a change of approximately 7 mV for a magnetic field change of ± 0.13 mT, resulting in a sensitivity of 24-25 V/T. The sinusoidal interference calculation using the wavenumber change due to a small magnetic field derived from the dispersion relation of spin waves agrees with the experimental results. This suggests that the mechanism of magnetic field detection is the wavenumber change due to the magnetic field.