Ferroelectronics Lab

Understanding and utilizing non-volatile properties of materials

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

By

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! “Intertwinded Polar, Chiral, and Ferro-Rotational Orders in a Homo-Ferro-Rotational Insulator”

By

Abstract: Intertwined orders refer to strongly coupled and mutually dependent orders that coexist in correlated electron systems, often underpinning key physical properties of the host materials. Among them, polar, chiral, and ferro-rotational orders have been theoretically known to form a closed set of intertwined orders. However, experimental investigation into their mutual coupling and physical consequences has remained elusive. In this work, we employ the polar-chiral insulator Ni3TeO6 as a platform and utilize a multimodal optical approach to directly probe and reveal the intertwining among polarity, chirality, and ferro-rotational order. We demonstrate how their coupling governs the formation of domains and dictates the nature of domain walls. Within the domains, we identify spatial inversion symmetry as the operation connecting two domain states of opposite polarity and chirality, with a homo-ferro-rotational state serving as the prerequisite for these interlocked configurations. At the domain walls, we observe a pronounced enhancement of in-plane polarization accompanied by a suppression of chirality. By combining with Ginzburg-Landau theory within the framework of a preexisting homo-ferro-rotational background, we uncover the emergence of mixed Néel- and Bloch-type domain walls. Our findings highlight the critical role of intertwined orders in defining domain and domain-wall characteristics and open pathways for domain switching and domain-wall control via intertwined order parameters.

Read more at Physical Review X

New Publication! “Signatures of quantum spin liquid state and unconventional transport in thin film TbInO3”

By

Abstract: Quantum spin liquids, where the frustrated magnetic ground state hosts highly entangled spins resisting long-range order to 0 K, are exotic quantum magnets proximate to unconventional superconductivity and candidate platforms for topological quantum computing. Although several quantum spin liquid material candidates have been identified, thin films crucial for device fabrication and further tuning of properties remain elusive. Recently, hexagonal TbInO3 has emerged as a quantum spin liquid candidate which also hosts improper ferroelectricity and exotic high-temperature carrier transport. Here, we synthesize thin films of TbInO3 and characterize their magnetic and electronic properties. Our films present a highly frustrated magnetic ground state without long-range order to 0.4 K, consistent with bulk crystals. We further reveal a rich ferroelectric domain structure and unconventional non-local transport near room temperature, suggesting hexagonal TbInO3 as a promising candidate for realizing exotic magnetic and transport phenomena in epitaxial heterostructures.

Read more at Nature Communications

Tony Chiang Defends His Thesis, Earning a PhD! Congratulations Tony!

By

Tony gave his defence today, 8/19/25, on the ““Polarization Evolution Behavior in
Scaled Ferroelectric Capacitors.” Here, he discussed his research which involved the development of ferroelectric capacitors down to 100 nm in lateral dimention. Using these capacitors, he explored three ferroelectric materials to identify their switching kinetics and limits. Here, he identified a circuit limited and material limited behavior regime differentiated by lateral dimention, the latter which is useful for accurately isolating materials properties. He also establishes a criteria for identifying this regime.

Congratulations Tony, great work!

New Publication! “Endotaxial Stabilization of 2D 1T-TaS2 Charge Density Waves via In-Situ Electrical Current Biasing”

By

Abstract: 1T-TaS2 is a layered, two-dimensional material which is host to several charge density wave (CDW) states with three distinct phases: an insulating commensurate (C) phase and the metallic nearly-commensurate (NC) and incommensurate (IC) phases [1-3]. CDW phase selection can be achieved via biasing, making 1T-TaS2 an attractive candidate for device applications [4-6]. The insulating C phase, however, only forms below ∼180 K [1, 7] for bulk 1T-TaS2 and even lower for thin flakes [5], leaving the metal-insulator transition unreachable for room temperature devices.

Recent work has shown endotaxial heterostructures of 2H-TaS2/1T-TaS2 can stabilize 2D C-CDW states in the twinned commensurate (tC) phase at room temperature with a single metal-insulator transition at ∼350 K [3, 8], paving the way for devices operable at room temperature. Previously, this phase has been realized by directly heating 1T-TaS2 past its polytype transition for a few minutes and then cooling it back to room temperature [3, 8].

Here, we show that the tC-CDW state can be synthesized electronically via current. Using an in-house built transmission electron microscopy (TEM) biasing holder, we can source current through exfoliated 1T-TaS2 flakes allowing us to drive and observe the polytype conversion in both real and reciprocal space in-situ. For sufficiently thin flakes, a current of around 210 µA/µm2 is enough to switch from the NC phase to the IC phase and back again. Upon sourcing higher currents of around 750 µA/µm2 the normal NC to IC transition is observed before seeing polytype conversion occur. Holding at this current for around 30 seconds longer is enough to stabilize the tC-CDW phase at room temperature. Similarly to the NC-IC transition, we can switch between the tC and IC phases of this new endotaxial structure by sourcing current through the sample. Using in-situ TEM we can correlate a polytype transition and the associated tC-CDW formation through electrical signatures. Further, this conversion is more localized compared to heating the sample in bulk.

In summary, we report current driven stabilization of 2D CDWs in 1T-TaS2 in and characterize the electronic switching of the NC to IC transition via in-situ TEM.

Read more at Microscopy and Microanalysis

About

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

News

Contact

Ferroelectronics Lab
Address: 2030 H.H. Dow

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