Pant, Rohit
Automated Materials Discovery Platform Realized: Scanning Probe Microscopy of Combinatorial Libraries
Liu, Yu, Pant, Rohit, Takeuchi, Ichiro, Spurling, R. Jackson, Maria, Jon-Paul, Ziatdinov, Maxim, Kalinin, Sergei V.
These libraries typically contain binary or ternary isothermal cross-sections of multicomponent phase diagrams, and more advanced synthesis methods can generate spatially encoded 4D and 5D compositional spaces [1]. This versatility makes them well-suited for both optimizing materials through direct exploration of compositional spaces and advancing physics discovery by exploring property and microstructure evolution [2-10]. Additionally, temperature gradients during synthesis can help reveal the effects of synthesis variables, while localized ion-or laser-based annealing enables broader exploration of the processing and chemical spaces within the selected material systems [8, 11, 12]. The first experiments in combinatorial research date back to the 1960s [13, 14], with renewed interest in the 1990s following the discovery of high-temperature superconductors [3, 4, 11, 15-17]. However, it quickly became apparent that successful combinatorial research requires not only synthesis but also detailed characterization, along with the ability to derive insights from characterization results and use these for subsequent experiment planning or transition towards different fabrication routes.
Real-time experiment-theory closed-loop interaction for autonomous materials science
Liang, Haotong, Wang, Chuangye, Yu, Heshan, Kirsch, Dylan, Pant, Rohit, McDannald, Austin, Kusne, A. Gilad, Zhao, Ji-Cheng, Takeuchi, Ichiro
Iterative cycles of theoretical prediction and experimental validation are the cornerstone of the modern scientific method. However, the proverbial "closing of the loop" in experiment-theory cycles in practice are usually ad hoc, often inherently difficult, or impractical to repeat on a systematic basis, beset by the scale or the time constraint of computation or the phenomena under study. Here, we demonstrate Autonomous MAterials Search Engine (AMASE), where we enlist robot science to perform self-driving continuous cyclical interaction of experiments and computational predictions for materials exploration. In particular, we have applied the AMASE formalism to the rapid mapping of a temperature-composition phase diagram, a fundamental task for the search and discovery of new materials. Thermal processing and experimental determination of compositional phase boundaries in thin films are autonomously interspersed with real-time updating of the phase diagram prediction through the minimization of Gibbs free energies. AMASE was able to accurately determine the eutectic phase diagram of the Sn-Bi binary thin-film system on the fly from a self-guided campaign covering just a small fraction of the entire composition - temperature phase space, translating to a 6-fold reduction in the number of necessary experiments. This study demonstrates for the first time the possibility of real-time, autonomous, and iterative interactions of experiments and theory carried out without any human intervention.
Multimodal Co-orchestration for Exploring Structure-Property Relationships in Combinatorial Libraries via Multi-Task Bayesian Optimization
Slautin, Boris N., Pratiush, Utkarsh, Ivanov, Ilia N., Liu, Yongtao, Pant, Rohit, Zhang, Xiaohang, Takeuchi, Ichiro, Ziatdinov, Maxim A., Kalinin, Sergei V.
The rapid growth of automated and autonomous instrumentations brings forth an opportunity for the co-orchestration of multimodal tools, equipped with multiple sequential detection methods, or several characterization tools to explore identical samples. This can be exemplified by the combinatorial libraries that can be explored in multiple locations by multiple tools simultaneously, or downstream characterization in automated synthesis systems. In the co-orchestration approaches, information gained in one modality should accelerate the discovery of other modalities. Correspondingly, the orchestrating agent should select the measurement modality based on the anticipated knowledge gain and measurement cost. Here, we propose and implement a co-orchestration approach for conducting measurements with complex observables such as spectra or images. The method relies on combining dimensionality reduction by variational autoencoders with representation learning for control over the latent space structure, and integrated into iterative workflow via multi-task Gaussian Processes (GP). This approach further allows for the native incorporation of the system's physics via a probabilistic model as a mean function of the GP. We illustrated this method for different modalities of piezoresponse force microscopy and micro-Raman on combinatorial $Sm-BiFeO_3$ library. However, the proposed framework is general and can be extended to multiple measurement modalities and arbitrary dimensionality of measured signals. The analysis code that supports the funding is publicly available at https://github.com/Slautin/2024_Co-orchestration.