Spin-wave spectroscopy of individual ferromagnetic nanodisks

TL;DR

This paper demonstrates a method for spatially resolved spin-wave spectroscopy of individual ferromagnetic nanodisks, enabling detailed magnetic property characterization of 3D nanostructures created by FEBID.

Contribution

It introduces a novel approach combining microwave antenna and microscopy for analyzing magnetic nanodisks down to 100 nm, advancing 3D nanomagnetism and magnonics.

Findings

Able to measure saturation magnetization and exchange stiffness.

Resolved standing spin-wave resonances in individual nanodisks.

Opens new possibilities for characterizing 3D magnetic nanostructures.

Abstract

The increasing demand for ultrahigh data storage densities requires development of 3D magnetic nanostructures. In this regard, focused electron beam induced deposition (FEBID) is a technique of choice for direct-writing of various complex nano-architectures. However, intrinsic properties of nanomagnets are often poorly known and can hardly be assessed by local optical probe techniques. Here, we demonstrate spatially resolved spin-wave spectroscopy of individual circular magnetic elements with radii down to 100 nm. The key component of the setup is a microwave antenna whose microsized central part is placed over a movable substrate with well-separated CoFe-FEBID nanodisks. The circular symmetry of the disks gives rise to standing spin-wave resonances and allows for the deduction of the saturation magnetization and the exchange stiffness of the material using an analytical theory. The presented approach is especially valuable for the characterization of direct-write elements opening new horizons for 3D nanomagnetism and magnonics.