Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:

Strain is powerful for discovery and manipulation of new phases of matter; however, elastic strains accessible to epitaxial films and bulk crystals are typically limited to small, uniform, and discrete values. In this talk I will describe our progress on synthesizing single crystalline membranes of Heusler compounds, which enable large continuously tunable strains and strain gradients via bending and rippling [1]. This synthesis strategy borrows ideas from remote epitaxy and van der Waals epitaxy on graphene, and I will describe our current understanding of the growth mechanisms [2,3]. I will then show how strain gradients transform rippled GdPtSb membranes from an antiferromagnet to a room temperature ferromagnet via flexomagnetic coupling [4], and how larger strain gradients induce flexomagnetism [5] and superconductivity in GdAuGe membranes. Finally, I will discuss new efforts on tuning ultrafast magnetism in membranes via combined strain and optical excitation. Our strained Heusler membranes offer a highly tunable platform for discovery of new topological, magnetic, and superconducting phases both in and out of equilibrium.

[1] D. Du, e. al. APL, 122, 170501 (2023).

[2] S. Manzo, et. al., Nature Commun., 13, 4014 (2022).

[3] D. Du et. al., Nano Lett. 22, 21, 8647 (2022).

[4] D. Du, et. al., Nature Commun., 12, 2494 (2021).

[5] Z. LaDuca, et. al. Nano Letters, 23, 33 (2024).

More about the Speaker:

Jason Kawasaki is an Associate Professor of Materials Science and Engineering at the University of Wisconsin – Madison. He received his BSE in Mechanical Engineering from Princeton University in 2009, Ph.D. in Materials from UCSB in 2014, and was a Kavli Postdoc at Cornell from 2014-2016. He joined UW-Madison in 2016. His research focuses on the epitaxial synthesis of magnetic and topological materials, especially Heusler compounds. Recent honors include the AVS Peter Mark Memorial Award (2024) and International Conference on Molecular Beam Epitaxy (ICMBE) Young Investigator (2024).