Abstract
We describe a spin wave modulator – spintronic device aimed to control spin wave propagation by an electric field. The modulator consists of a ferromagnetic film serving as a spin wave bus combined with a synthetic multiferroic comprising piezoelectric and magnetostrictive materials. Its operation is based on the stress-mediated coupling between the piezoelectric and magnetostrictive materials. By applying an electric field to the piezoelectric layer, the stress is produced. In turn, the stress changes the direction of the easy axis in the magnetostrictive layer and affects spin wave transport. We present experimental data on a prototype consisting of a piezoelectric [Pb(Mg1/3Nb2/3)O3](1-x) –[PbTiO3]x substrate, and 30 nm layer of magnetostrictive Ni film, where the film is attached to a 30 nm thick Ni81Fe19 spin wave bus. We report spin wave signal modulation in Ni81Fe19 layer by an electric field applied across the piezoelectric layer. The switching between the spin wave conducting and non-conducting states is achieved by applying ±0.3 MV/m electric field. We report over 300% modulation depth detected 80 μm away from the excitation port at room temperature. The demonstration of the spin wave modulator provides a new direction for spin-based device development by utilizing an electric field for spin current control.
Highlights
During the past decade, there has been a growing interest in spin wave logic devices and several working prototypes have been demonstrated[12,13,14,15,16]
From the bottom to the top, it consists of a semiconductor substrate, a conducting ferromagnetic film (e.g., CoFe, NiFe), a layer of magnetostrictive material (e.g., Ni), and a piezoelectric layer (e.g., 011 PMN-PT)
We described a spin wave modulator, which operation is based on the stress-mediated coupling between piezoelectric and magnetostrictive materials
Summary
There are several unique properties of the described modulator to be outlined and discussed. Spin wave propagation is controlled by applying an electric field. The latter produces minimal power consumption compared to conventional methods. The artificial multiferroic element is analogous to a parallel plate capacitor, where one of the plates is made of a magnetostrictive material. The charging/discharging of the capacitor affects the magnetic properties of the magnetostrictive material via the stress-mediated coupling. A relatively weak electric field Esw (e.g., 0.6 MV/m for PMN-PT/Ni/Py structure) is required to switch between the spin-wave conducting and spin wave non-conducting regimes. The energy dissipated in the multiferroic element Ε can be estimated as follows: Ε
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