Spin-wave propagation in the presence of inhomogeneous Dzyaloshinskii-Moriya interactions

Abstract

We theoretically investigate spin-wave propagation through a magnetic metamaterial with spatially modulated Dzyaloshinskii-Moriya interaction. We establish an effective Schrödinger equation for spin waves and derive boundary conditions for spin waves passing through the boundary between two regions having different Dzyaloshinskii-Moriya interactions. Based on these boundary conditions, we find that the spin wave can be amplified at the boundary and the spin-wave band gap is tunable either by an external magnetic field or the strength of Dzyaloshinskii-Moriya interaction, which offers a spin-wave analog of the field-effect transistor in traditional electronics.

Spin Waves in Thin Films and Magnonic Crystals with Dzyaloshinskii–Moriya Interactions

“…In particular, this numerical technique can be used to calculate the spectrum of spin waves, and when a DMI is present, it reveals different properties characteristic of these systems, such as the spin-wave asymmetry. In this context, simulations have successfully supported theoretical formulations [80,96,97,99,[132][133][134][135][136][137] and experimental measurements [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87]138] on thin-film systems with a homogeneous DMI. A micromagnetic simulation is based on numerically discretizing the continuum description of the magnetic system into a mesh of magnetic moments whose arrangement depends on the discretization method.…”

Goos-Hänchen effect of spin waves at heterochiral interfaces

“…The evaluation of the reflection and transmission coefficients requires boundary conditions for spin waves at the heterochiral interface, which are derived below. By defining a spin-wave function Φ = m x + im z and neglecting the damping, we linearize the LLG equation ( 1) and recast it into an effective Schrödinger equation [19]:…”

“…The Dzyaloshinskii-Moriya interaction (DMI) [8,9], present in magnetic materials with broken inversion symmetry, has a chiral character and causes the nonreciprocal propagation of spin waves [10][11][12][13], which provides additional functionalities in magnonic devices [14][15][16][17][18]. Recent works found that magnonic crystals with a periodic DMI can efficiently modulate spin-wave propagations and give rise to a plethora of unique effects, such as the spin-wave amplification [19], the emergence of indirect gaps, the formation of flat bands, and an unconventional evolution of the standing spin waves around the gaps [20]. Recently, it has been shown that total reflections and negative refractions can occur at the DMI interface and the spin-wave refraction is not symmetric for positive and negative incident angles [21,22].…”

Magnetic texture based magnonics

“…Section 2.2) [388]. Furthermore, periodical inhomegeneous DMI [407] can result in spin-wave band gaps [405] in a chiral magnonic crystal [408,409,410].…”