January: Mehrdad Kiani

Thermomechanical nanomolding of topological compounds

Mehrdad Kiani

Cornell University (Cha group)

Wednesday, January 24, 2024

2:00 pm ET/11:00 am PT

Abstract:

Theoretical calculations have shown that ~27% of known crystalline materials may be topological [1], giving researchers and scientists a large materials playground to study new topological states and identify promising compounds. While bulk single crystals are typically used to study topological states, fabrication of nanostructures over wafer-scale distances with tailored morphological features and chemical composition is necessary for any potential application such as microelectronics or functional devices. Given the vast number of potential candidates to screen, no currently developed nanofabrication technique is sufficiently high throughput. In this talk, I will discuss my recent work using thermomechanical nanomolding (TMNM) to fabricate topological compounds at the nanoscale. TMNM is a new nanofabrication technique whereby a bulk polycrystalline feedstock is pressed through a nanoporous mold at elevated temperatures and pressures. Compared to more traditional nanofabrication, TMNM is scalable, requires minimal optimization, and works on a wide range of materials including metals, alloys, intermetallics, and 2D materials. I will show my recent results using TMNM to fabricate nanowires with different chemistry and crystal structures and single crystal nanoribbons over millimeter length scales.

[1] Vergniory, M. G. et al. A complete catalogue of high-quality topological materials. Nature. 2019 5667745 566, 480–485 (2019).

Bio:

Mehrdad Kiani is a postdoctoral associate at Cornell University in the lab of Judy Cha. His research interests include development of new nanomanufacturing techniques, in situ electron microscopy, and nanomechanics. He received his Ph.D. as a NDSEG Fellow from Stanford University in Materials Science in 2021 in the lab of Wendy Gu.