Daniel Durham, PhD
Assistant Scientist
Center for Nanoscale Materials
Argonne National Laboratory
Monday April 28, 2025 | Seminar: 2 p.m. | 230 A Davis Hall
Materials with enhanced electronic responses, such as ferroics and phase transitions, are of great interest for improving current technologies as well as enabling new paradigms such as neuromorphics. However, as electronics become smaller and faster, material responses can change, and defects and interfaces can play important roles. So, it is important to characterize the relationships between structure, properties, and dynamics of such materials at the relevant nanoscopic dimensions and nanosecond or faster timescales.
In this seminar, I will present electron microscopy developments and studies towards meeting these challenges. First, I will introduce “voltage-triggered ultrafast electron microscopy,” which we developed to image electrical switching dynamics with nanometer and nanosecond resolution. Using this, I will show how we captured the debated electrical switching mechanism of charge density waves in 1T-TaS2 at room temperature, revealing a two-part switching mechanism [1]. Second, I will introduce electron microscopy approaches for mapping local structure and electrostatics. Using this, I will show how we examined contributions of defects and interfaces to the electronic response of hafnia-zirconia ferroelectric nanocapacitors, including asymmetric interfaces and built-in fields [2]. Finally, I will discuss opportunities to apply these approaches to other important research questions in electronic materials and devices.
[1] Durham DB et al. “Nanosecond Structural Dynamics during Electrical Melting of Charge Density Waves in 1T-TaS2.” Phys. Rev. Lett. 2024, 132(22), 226201.
[2] Durham DB et al. “Direct Imaging of Asymmetric Interfaces and Electrostatic Potentials inside a Hafnia–Zirconia Ferroelectric Nanocapacitor.” ACS Appl. Mater. Interfaces. 2024, 16(49), 68562-8.