An Efficient Algorithm for Automatic Structure Optimization in X-ray Standing-Wave Experiments

TL;DR

This paper introduces SWOPT, an automated, efficient algorithm for optimizing the analysis of X-ray standing-wave data in multilayered samples, significantly reducing analysis time and enabling real-time experimental feedback.

Contribution

The authors developed SWOPT, a novel computer program that automates and accelerates structure optimization in X-ray standing-wave experiments, improving speed and accuracy over manual methods.

Findings

SWOPT finds better solutions faster than random search.

Optimization time ranges from minutes to hours, up to 100x faster than manual.

Program enables real-time data analysis during experiments.

Abstract

X-ray standing-wave photoemission experiments involving multilayered samples are emerging as unique probes of the buried interfaces that are ubiquitous in current device and materials research. Such data require for their analysis a structure optimization process comparing experiment to theory that is not straightforward. In this work, we present a new computer program for optimizing the analysis of standing-wave data, called SWOPT, that automates this trial-and-error optimization process. The program includes an algorithm that has been developed for computationally expensive problems: so-called black-box simulation optimizations. It also includes a more efficient version of the Yang X-ray Optics Program (YXRO) [Yang, S.-H., Gray, A.X., Kaiser, A.M., Mun, B.S., Sell, B.C., Kortright, J.B., Fadley, C.S., J. Appl. Phys. 113, 1 (2013)] which is about an order of magnitude faster than the original version. Human interaction is not required during optimization. We tested our optimization algorithm on real and hypothetical problems and show that it finds better solutions significantly faster than a random search approach. The total optimization time ranges, depending on the sample structure, from minutes to a few hours on a modern laptop computer, and can be up to 100x faster than a corresponding manual optimization. These speeds make the SWOPT program a valuable tool for realtime analyses of data during synchrotron experiments.