Piezoelectric tuning of the resonance frequency in the synthetic multiferroic structures α-Fe2O3/68%Pb(Mg1/3Nb2/3)O3-32%PbTiO3 in the sub-THz range

In this article, we present the results of studies carried out on the synthetic multiferroic structure α-Fe2O3/68%Pb(Mg1/3Nb2/3)O3-32%PbTiO3 (PMN-PT). The thicknesses of the α-Fe2O3 single crystal and PMN-PT piezoelectric substrate were 500 μm. Using Brillouin light scattering spectroscopy, we experimentally studied the excitation of quasi-ferro- and antiferromagnetic modes of α-Fe2O3, as well as the effect of induced deformations from the polarized piezoelectric layer on the frequencies of quasi-ferro- and antiferromagnetic modes. For the PMN-PT [001] and [011] cuts, we considered the dependencies of the frequency of the quasi-ferromagnetic mode on the in-plane rotation of the magnetic field at the applied electric field with a voltage of 0–1000 V and on the magnetic field at ϕH=0° and ϕH=45°. We built a model that describes the linear piezoelectric and the nonlinear electrostrictive contributions, which was applied to the “butterfly-shaped” strain–voltage characteristic of the PMN-PT and the following hysteresis shift of antiferromagnetic resonance frequency with an applied electric field of 0–1000 V. We proved that by applying voltage to the PMN-PT substrate, it was possible to achieve a significant tuning of the antiferromagnetic resonance mode frequency (up to 10%). Our results show that such a synthetic multiferroic structure is a suitable component for magnonic devices with frequency tuning in the GHz and sub-THz frequency ranges.