Coherent terahertz spin-wave emission associated with ferrimagnetic domain wall dynamics

Abstract

We theoretically study the dynamics of ferrimagnetic domain walls in the presence of Dzyaloshinskii-Moriya interaction. We find that an application of a DC magnetic field can induce terahertz spin-wave emission by driving ferrimagnetic domain walls, which is not possible for ferromagnetic or antiferromagnetic domain walls. Dzyaloshinskii-Moriya interaction is shown to facilitate the teraherz spin-wave emission in wide ranges of net angular momentum by increasing the Walkerbreakdown field. Moreover, we show that spin-orbit torque combined with Dzyaloshinskii-Moriya interaction also drives a fast ferrimagnetic domain wall motion with emitting terahertz spin-waves in wide ranges of net angular momentum.

Novel interpretation of recent experiments on the dynamics of domain walls along ferrimagnetic strips

“…This expression recalls the Walker field for FMs, [14] but adds a factor depending inversely on δ s . The expression generalizes that obtained in the literature from an effective model, [15] where Gilbert damping values are taken as identical for both SL, and diverge at T A . FIG.2 Figure 2.…”

Magnetic and magneto-transport properties of Mn4N thin films by Ni substitution and their possibility of magnetic compensation

“…13 For instance, the DW velocity (v DW ) in a Gd 44 Co 56 ferrimagnetic nanowire has been reported to reach a record value of 1.3 km/s close to T A (260 K). 14 Moreover, many experiments and discussions have also been conducted on the operation of ferrimagnetic materials at T A regarding other aspects such as spin-wave emission, 15 Dzyaloshinskii-Moriya interaction, 16 and maximized exchange coupling torque. 17 In this context, we have paid special attention to ferrimagnetic Mn 4 N, which is composed of abundant and inexpensive elements.…”

Electrical Generation and Detection of Terahertz Signal Based on Spin-Wave Emission From Ferrimagnets

“…In addition, vDW without Lorentz contraction at Aex = 8 meV and Jc = 10 12 A m -2 is 5.9 km s -1 , which is four times larger than that from the atomistic simulation. To resolve these discrepancies, it has been pointed out that the DW motion in AFMs or FiMs with large DMI requires additional consideration of the relativistic effect [19,21], which imposes the Lorentz contraction on λ, resulting in the deviation from its equilibrium value (λeq) by a factor of √1 − ( DW / g,max ) 2 ,…”