Element-Specific First Order Reversal Curves Measured by Magnetic Transmission X-ray Microscopy

TL;DR

This paper demonstrates the use of magnetic transmission X-ray microscopy to perform element-specific first order reversal curves, revealing microscopic magnetic domain evolution and enabling measurements on small, complex nanoscale structures.

Contribution

It introduces a novel combination of FORC measurements with MTXM for element-specific, high-resolution magnetic analysis at the nanoscale, including buried layers and microstructures.

Findings

Good quantitative agreement with magnetometry FORCs

Visualization of domain evolution during magnetic cycling

Successful measurement on microstructures with vortex-like Landau structures

Abstract

The first order reversal curve (FORC) method is a macroscopic measurement technique which can be used to extract quantitative, microscopic properties of hysteretic systems. Using magnetic transmission X-ray microscopy (MTXM), local element-specific FORC measurements are performed on a 20 nm thick film of CoTb. The FORCs measured with microscopy reveal a step-by-step domain evolution under the magnetic field cycling protocol, and provide a direct visualization of the mechanistic interpretation of FORC diagrams. They are compared with magnetometry FORCs and show good quantitative agreement. Furthermore, the high spatial resolution and element-specific sensitivity of MTXM provide new capabilities to measure FORCs on small regions or specific phases within multicomponent systems, including buried layers in heterostructures. The ability to perform FORCs on very small features is demonstrated with the MTXM-FORC measurement of a rectangular microstructure with vortex-like Landau structures. This work demonstrates the confluence of two uniquely powerful techniques to achieve quantitative insight into nanoscale magnetic behavior.