Field-controlled ultrafast magnetization dynamics in two-dimensional nanoscale ferromagnetic antidot arrays.

Anulekha De,Anjan Barman,Sourav Sahoo,Yoshichika Otani,Rajib Kumar Mitra,Sucheta Mondal,Saswati Barman

doi:10.3762/bjnano.9.104

Abstract

Ferromagnetic antidot arrays have emerged as a system of tremendous interest due to their interesting spin configuration and dynamics as well as their potential applications in magnetic storage, memory, logic, communications and sensing devices. Here, we report experimental and numerical investigation of ultrafast magnetization dynamics in a new type of antidot lattice in the form of triangular-shaped Ni80Fe20 antidots arranged in a hexagonal array. Time-resolved magneto-optical Kerr effect and micromagnetic simulations have been exploited to study the magnetization precession and spin-wave modes of the antidot lattice with varying lattice constant and in-plane orientation of the bias-magnetic field. A remarkable variation in the spin-wave modes with the orientation of in-plane bias magnetic field is found to be associated with the conversion of extended spin-wave modes to quantized ones and vice versa. The lattice constant also influences this variation in spin-wave spectra and spin-wave mode profiles. These observations are important for potential applications of the antidot lattices with triangular holes in future magnonic and spintronic devices.

Highlights

Recent advances in nanofabrication techniques have resulted in artificially patterned magnetic metamaterials, known as magnonic crystals (MCs), which have great potential for technological applications and fundamental research [1,2]
The scanning electron micrographs (SEMs) images show that the triangular antidots have rounded corners and they suffer from small asymmetry in their shapes
In conclusion we have investigated the effects of the orientation of the bias-magnetic field and lattice constant on the ultrafast magnetization dynamics and magnetostatic field distribution in a periodic array of triangular nanoholes forming a hexagonal antidot lattice in a thin Py film by using time-resolved Kerr microscopy

Summary

Introduction

Recent advances in nanofabrication techniques have resulted in artificially patterned magnetic metamaterials, known as magnonic crystals (MCs), which have great potential for technological applications and fundamental research [1,2]. We have investigated the variation in the nature of the extended and quantized SW modes in such systems by changing the strength and orientation of the in-plane bias-magnetic field and the lattice constant of the array.

Results

Conclusion