Reconfigurable Ferromagnetic Resonances by Engineering Inhomogeneous Magnetic Textures in Artificial Magnonic Crystals

Abstract

Advanced microfabrication gives rise to an extra degree of freedom for controlling magnetic textures, which determine the spin dynamics of thin‐film magnets for various spintronic devices. However, the intuitive understanding of complicated ferromagnetic resonances (FMRs) is still challenging for lacking directly observed evolution of inhomogeneous magnetic textures. This study demonstrates the reconfigurable FMRs by introducing artificial patterns of antidot lattices (namely magnonic crystals), mediated by the engineering of inhomogeneous magnetic textures. Ordered walls are observed directly in such a magnetic film using in situ Lorentz transmission electron microscopy. By applying in‐plane external magnetic fields, arc‐shaped domain walls can be nucleated along the edge of patterns, inducing the splitting of FMRs from a single peak to two branches (marked by low‐frequency and high‐frequency branches, respectively). Complementary micromagnetic simulations reconstruct the inhomogeneous magnetic textures and splitting of FMRs. It is indicated that the low‐frequency branch ascribes to the confined mode excited by arc‐shaped domain walls, and the high‐frequency one originates from the quasi‐uniform mode generated by in‐plane magnetization between arc‐shaped domain walls. These results offer new opportunities for designing patterned magnonic devices and understanding the unique phenomenon of spin dynamics.

Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe12‐Based Permanent Magnets

“…Figure S4b,c, Supporting Information shows the magnetic domain structures for the area composed of both phases. The typical strip domains and vortex domains are observed for the hard magnetic ThMn 12 -type phase [5] and soft magnetic α-FeCo phase, [31] respectively. The continuous domain walls and magnetic moments at the interface of two phases (marked areas C and D) depict the strong magnetic exchange coupling.…”

The Developed Wave Cancellation Theory Contributing to Understand Wave Absorption Mechanism of ZIF Derivatives with Controllable Electromagnetic Parameters

“…[20] Oxidation of surface metals introduces more interfaces and provides rich interfacial polarization. [21] The hysteresis lines of the Co@NC samples show that the magnetic coercivity (H c ), residual magnetization (M r ), and saturation magnetization (M s ) strength of the all samples increase with increasing temperature in the same heat treatment atmosphere, except for H800 where M s decreases compared to H700 (Figure 3f and Figure S7, Supporting Information). This is due to the fact that the more ordered the crystal structure of the magnetic nanoparticles, the greater the magnetic crystal anisotropy energy and the greater the H c and M r .…”

Connection Between Intrinsic Interfacial Frozen Spins and Exchange Bias Effect in Core@Shell Iron@Iron‐Oxide Nanoparticles

“…Thus, the relative magnitude of frozen spins (M f /M þ ) can be 0.56% by calculating the net moment of frozen spins with [55,56] To understand the origin of the exchange bias effect, we assumed the exchange bias induced by frozen spins as the synergy of an effective static magnetic field and an effective anisotropy. Using micromagnetic simulations, [57][58][59] hysteresis loops with different static magnetic fields and anisotropy constants were calculated for core@shell Fe@Fe-oxide nanoparticles. As shown in Figure 5a, the increase of coercivity can be reconstructed by introducing an effective anisotropy constant (K e ) of the shell.…”