Nonresonant amplification of spin waves through interface magnetoelectric effect and spin-transfer torque

Abstract

We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices.

Finite Element Approach for the Simulation of Modern MRAM Devices

“…The torque term entering ( 1 ) can be computed from the spin accumulation through the following expression [ 16 , 30 , 31 , 32 ]: The first term describes the precession around the exchange field and is characterized by the exchange length , and the second term describes the dephasing process of the spins of the transiting electrons, and is characterized by the dephasing length . is the electron diffusion coefficient.…”

“…The torque term T S entering (1) can be computed from the spin accumulation through the following expression [16,[30][31][32]:…”

Theory of drift-enabled control in nonlocal magnon transport

“…Due to the generally non-conserved nature of spin, a range of phenomena not admitted by electric current become feasible. Exploiting this principle, coherent spin waves generated using a microwave antenna can be amplified via various mechanisms, such as charge current [1,19,20], spin transfer torque [21][22][23][24], and thermal gradient [25][26][27]. Furthermore, attributes such as chirality can be bestowed upon the different spin wave modes via engineering of the energy landscape in the host magnet [28][29][30][31][32][33][34][35][36][37][38].…”

Theory of drift-enabled control in nonlocal magnon transport

“…Due to the generally non-conserved nature of spin, a range of phenomena not admitted by electric current become feasible. Exploiting this principle, coherent spin waves generated using a microwave antenna can be amplified via various mechanisms, such as charge current [1, 19,20], spin transfer torque [21][22][23][24], and thermal gradient [25][26][27]. Furthermore, attributes such as chirality can be bestowed upon the different spin wave modes via engineering of the energy landscape in the host magnet [28][29][30][31][32][33][34][35][36][37][38].…”