Ferroelectronics Lab

Understanding and utilizing non-volatile properties of materials

Our Research in the News: Beyond transistor limits: Hybrid magnetic-sound waves could boost computing speed and efficiency

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The Ferroelectronics Lab finds itself in the news once again thanks to a collaborative project funded by the Defense Advanced Research Projects Agency (DARPA), which offers a $6 million budget. In this DARPA “fast and curious” project, we are working together with Dr. Roozbeh Tabrizian, Dr. Wei Lu, both professors here at the University of Michigan, and Dr. Jiamian Hu, a professor at the University of Wisconsin-Madison to develop a novel magnetoacoustic device. If successful, “new devices made of combined ferroelectric and ferromagnetic materials (magnetoelectric multiferroics) could radically improve the speed and energy efficiency of computer processors and also add memory capability.” In our lab, specifically Pat Kezer and Avery Ansbro are contributing to this project.

See the Michigan Engineering newsletter here to learn more about this project.

Our Research in the News: New Model Bridges Ferroelectric Physics and Circuit Modeling

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Our recent publication written by Yi Liang “Ferroelectric Dynamic-Field-Driven Nucleation and Growth Model for Predictive Materials-To-Circuit Co-Design,” has caught the attention of the University news. Highlighted on the University Engineering website and on TechXplore, the development of a dynamic-field-driven nucleation and growth (DFNG) model allows for the prediction of ferroelectric behavior under real-world, complex voltages. This bridges the longstanding gap between fundamental switching physics and practical device engineering. Congratulations to Yi and her collaborators on this achievement.

Read the article at University of Michigan Engineering News or TechXplore or look at the publication directly at Advanced Materials

New Publication! “Ferroelectric Dynamic-Field-Driven Nucleation and Growth Model for Predictive Materials-To-Circuit Co-Design”

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Abstract: Real ferroelectric devices operate under mixed and distorted time-varying voltages, yet the standard nucleation-growth frameworks used to interpret ferroelectric switching, most notably the Kolmogorov-Avrami-Ishibashi (KAI) and nucleation-limited switching models (NLS), are derived under the critically limiting assumption of a constant electric field. Thus, the prevailing interpretation of ferroelectric switching dynamics fails under real operating conditions. Here we introduce a compact dynamic-field-driven nucleation and growth (DFNG) model that enables quantitative fits to switching transients across multiple ferroelectric materials to extract time-varying domain wall velocity and growth dimensionality, even under arbitrary voltage waveforms. This capability then motivates its use in device modeling under complex signals spanning disparate time and frequency scales. Coupling the compact model to application-related waveforms and a circuit-level simulation platform facilitates a predictive materials-circuit co-design framework by linking nucleation and growth parameters to memory window, disturb error, speed, and energy dissipation for next-generation ferroelectric technologies.

Read more at Advanced Materials

New Publication! “Evidence of Local Structural Variations and Their Influence on Magnetic Properties in Mn- and Cr-Containing High-Entropy Oxide Thin Films Using Electron Microscopy”

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Abstract: Alloying is an age-old strategy for synthesizing materials with enhanced properties. Recently, multicomponent systems such as high-entropy oxides have garnered widespread attention due to their tunable and often superior properties compared to their constituent oxides. Here, we study the local structural and chemical nuances of six-component (Mg0.167Co0.167Ni0.167Cu0.167Zn0.167Mn0.167)O and (Mg0.167Co0.167Ni0.167Cu0.167Zn0.167Cr0.167)O thin films. The Mn-alloyed thin film exhibits a higher exchange bias and greater magnetic frustration compared with the Cr-containing thin film. Scanning/transmission electron microscopy investigations reveal that the Mn-alloyed thin film exhibits the coexistence of rock salt and spinel-like regions, unlike the single-phase rock salt structure observed in the Cr-alloyed thin film. Electron energy loss spectroscopy indicates changes in Co and Mn valences within the Mn-containing thin film, suggesting the presence of mixed-valence states, which are further confirmed by X-ray absorption spectroscopy measurements. These observations are further validated by cation-site-preference energy calculations using density functional theory. Our results demonstrate how the chemistry, site occupations, and cation valences result in pronounced changes in the overall properties of high-entropy oxides.

Read more at Journal of the American Chemical Society

New Publication! “Historical Foundation and Practical Guideline for Ferroelectric Switching Kinetic Studies”

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Abstract: Electrical measurements of ferroelectric switching kinetics are widely used to probe the dynamics of polarization reversal, yet the influence of the measurement circuit is often underappreciated. In this paper, we show that the interplay between ferroelectric capacitors and circuit elements produces distorted, time-dependent voltage waveforms across the device, particularly in the sub-ns regime. We examine how these circuit contributions affect polarization transients extracted from PUND measurements. The resulting distortions scale with supply voltage, capacitor dimensions, and lumped circuit elements, but are not accounted for in conventional experimental analyses or analytical model fitting. We then critically assess existing nucleation and growth models and show that neglecting the time-varying voltage profile can lead to unphysical interpretations of switching kinetics, most notably in the extracted growth dimensionality represented by the Avrami exponent. Finally, we outline guidelines for future studies, emphasizing the need for direct voltage monitoring and circuit-aware de-embedding, as well as modeling frameworks that incorporate voltage-dependent nucleation and growth rates based on intrinsic material parameters.

Read more at Advanced Functional Materials

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Our research is at the intersection of multiple disciplines, drawing on principles and methodologies from materials science, chemistry, physics, and electrical engineering. Our mission is to pioneer … Read More

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Ferroelectronics Lab
Address: 2030 H.H. Dow

T: (734) 763-6914
E: jtheron@umich.edu