Magnetic imaging with full-field soft X-ray microscopies

Abstract

Progress toward a fundamental understanding of magnetism continues to be of great scientific interest and high technological relevance. To control magnetization on the nanoscale, external magnetic fields and spin polarized currents are commonly used. In addition, novel concepts based on spin manipulation by electric fields or photons are emerging which benefit from advances in tailoring complex magnetic materials. Although the nanoscale is at the very origin of magnetic behavior, there is a new trend toward investigating mesoscale magnetic phenomena, thus adding complexity and functionality, both of which will become crucial for future magnetic devices.Advanced analytical tools are thus needed for the characterization of magnetic properties spanning the nano-to the meso-scale. Imaging magnetic structures with high spatial and temporal resolution over a large field of view and in three dimensions is therefore a key challenge. A variety of spectromicroscopic techniques address this challenge by taking advantage of variable-polarization soft X-rays, thus enabling X-ray dichroism effects provide magnetic contrast. These techniques are also capable of quantifying in an element-, valence-and site-sensitive way the basic properties of ferro(i)-and antiferro-magnetic systems, such as spin and orbital moments, spin configurations from the nano-to the meso-scale and spin dynamics with sub-ns time resolution. This paper reviews current achievements and outlines future trends with one of these spectromicroscopies, magnetic full field transmission soft X-ray microscopy (MTXM) using a few selected examples of recent research on nano-and meso-scale magnetic phenomena. The complementarity of MTXM to X-ray photoemission electron microscopy (X-PEEM) is also emphasized.

Unveiling the Emergent Traits of Chiral Spin Textures in Magnetic Multilayers

“…MTXM Experiments: Full-field MTXM imaging experiments were performed using circularly polarized soft X-rays at the advanced light source (XM-1 BL 6.1.2), using the Co L3 edge (≈778 eV) with OP sample geometry. [37] OP magnetic fields were applied using an electromagnet, and a pair of horse-shoe poles were used to guide the generated flux.…”

“…Notably, the field-induced variation of W, or dW/dHtermed as domain compressibility [35] -should also evolve with 𝜅. [4,25,36] MTXM imaging-wherein magnetic circular dichroic contrast is proportional to local OP magnetization [37] -is wellsuited to measure W. Therefore, we performed MTXM imaging with varying OP field using samples deposited on Si 3 N 4 membranes, complemented by micromagnetic simulations (see Experimental Section). W was determined as an averaged quantity over the full field-of-view of about 5 μm using an automated recipe to mitigate granularity effects (see Section S2, Supporting Information).…”

Unveiling the emergent traits of chiral spin textures in magnetic multilayers

“…Notably, the field-induced variation of W , or dW /dHtermed as domain compressibility 35 -should also evolve with κ 4,25,36 . MTXM imaging -wherein magnetic circular dichroic contrast is proportional to local OP magnetization 37 -is well-suited to measure W . Therefore, we performed MTXM imaging with varying OP field using samples deposited on Si 3 N 4 membranes, complemented by micromagnetic simulations (see Experimental Section).…”

“…Full-field MTXM imaging experiments were performed using circularly polarised soft x-rays at the Advanced Light Source (XM-1 BL 6.1.2), using the Co L3 edge (∼778 eV) with outof-plane (OP) sample geometry 37 . OP magnetic fields were applied using an electromagnet, and a pair of horse-shoe poles were used to guide the generated flux.…”

Magnetic Imaging and Microscopy

“…Transmission x-ray microscopy (TXM) [94,95] can be seen as an analog to visible light microscopy, with enhanced resolution by using smaller probing wave lengths. Lenses at the wavelengths of soft x-rays are realized by diffractive elements, so-called zone plates.…”