Abstract
Combined ab initio and micromagnetic simulations are carried out to demonstrate the feasibility on the electrical manipulation of spin-wave propagation in ultrathin Fe films. It is discovered that the exchange interaction can be substantially weakened under the influence of electric field applied perpendicular to the magnetic film surface. Furthermore, we demonstrate that the electric field modified exchange constant could effectively control the propagation of spin waves. To be specific, an external applied electric field of 5 V/nm can effectively weaken exchange interaction by 80% and is sufficient to induce nearly twofold change of the wavenumber. This discovery may open a door to energy-efficient local manipulation of the spin wave propagation utilizing electric fields, which is crucial for both fundamental research and spin wave based logic applications.
Highlights
Magnonics is deemed as the most promising candidate for information transmission and processing[1,2,3,4] where information is carried by the collective precession of the electrons’ spin instead of dissipative translation of their charge
Ab initio calculations are carried out to investigate the direct influence of an external electric field on exchange constant based on density function theory
Micromagnetic modelings of spin waves propagating in thin film under influence of electric fields are implemented with parameters obtained by ab initio calculations
Summary
First principles calculations based on density functional theory[17,18,19] (DFT) were performed using the Vienna ab initio simulation package[20,21] (VASP) to elucidate the magnetoelectric effect on the exchange constant quantitatively under the influence of a uniform electric field applied perpendicular to the film surface. There is an enhancement in magnetic moment at the surface, originating from sudden change in the electronic structure of the atomic orbitals along the direction perpendicular to the surface as compared with the bulk due to the break of symmetry at the surface[31] In the latter part of this article, we proposed a novel electrical modulation technique of spin wave length and phase velocity, using object-oriented micromagnetic framework[32] with variable exchange interactions by the application of electric fields, d →m dt. Utilizing the dependence of the carrier wave number of the spin-wave for a given carrier frequency on the external electric field applied perpendicular to the ferromagnetic film, it is easy to implement electric-field-controlled phase shifter. It rarely consumes power dissipation except for the charge/discharge period during which the control state switches
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