Researchers in the Wisconsin MRSEC have shown that bilayer electron crystals exhibit a variety of magnetic states depending on the distance between the two layers and the number of electrons in each layer. These state include ferromagnetic and antiferromagnetic arrangements of electron spins, as well as exotic states like the valence-bond solid and spin-nematic. These results establish bilayer crystals as a promising platform for studying quantum magnetism and provide guidance for experiments characterizing electron solids realized in 2D materials.
Center Highlights
(2025) Spin-Mechanical Coupling Wisconsin MRSEC in 2D Antiferromagnet CrSBr
Wisconsin MRSEC researchers have demonstrated that strain can dramatically alter the magnetoelastic properties of a two-dimensional material, CrSBr. Magnetoelasticity is the interaction between magnetism and strain. The researchers developed a nanoscale mechanical resonator device to measure the material’s magnetoelastic coupling. Using it, they showed that 2D CrSBr has a particularly large coupling, and that it can be tuned by 50% by stretching the 2D membrane.
(2025) Geometrically Accurate Coarse-Graining with AniSOAP
Wisconsin MRSEC researchers have developed a coarse-graining technique called AniSOAP (for anisotropic smooth overlap of atomic potentials) that gives the beads shapes that reflect the shape of the molecules they represent. This simple idea – carefully implemented to be mathematically rigorous and account for how molecules typically interact – can used for high-accuracy coarse grained simulations or to understand materials behavior that depends on molecular shape or orientation. AniSOAP is also particularly useful for machine learning analysis of molecular behavior using simple, physically-interpretable algorithms, producing new insight for researchers.
(2025) A Nanoscale View of Molecule Alignment in an Organic Semiconductor
Wisconsin MRSEC researchers have developed a new way to see how molecules fit together with an electron microscope. They used the method to see how molecules rearrange when an organic semiconductor is heated. A modest change in temperature creates significantly improved molecular alignment. The improved alignment is reflected in both larger aligned regions and straighter lines of molecules inside each region.
(2024) Instrumentation for Ultrafast Broadband Spectroscopy for Resonant Magnetic and Phononic Excitations
Researchers in Wisconsin MRSEC IRG 2 have developed instrumentation to use light to study magnetism, vibrations, and their couplings in thin crystal membranes as they are pulled and bent. These phenomena cover a range of wavelength from nanometers to millimeters and they respond in as little as 10-15 s (a femtosecond). The instruments developed by IRG 2 cover this entire range of wavelengths and timescales, making them a powerful suite of tools for MRSEC research.
(2024) Reaching Underserved Communities with Materials Science Outreach through Partnership
The Wisconsin MRSEC has partnered with the Morgridge Institute for Research to bring scientific outreach to underserved communities. Afterschool programs, especially programs that serve economically disadvantaged students, can face major barriers to bringing students to campus for STEM outreach activities. To increase access, the Morgridge Institute has created Afterschool Expeditions, a program that brings UW-Madison research-inspired STEM outreach to students in their programs instead asking them to come to campus.
(2024) RET Fellow and MRSEC Research Team Continue to Support Student Outreach through Mentorship Program
Wisconsin MRSEC Research Experience for Teachers 2022 fellow Lalitha Murali leveraged her connection with Jason Kawasaki in Wisconsin MRSEC IRG 2 and support from a Agris-Pine grant from the Society for Science to arrange science project mentors for 7th grade students from her Title I school in Milwaukee.
(2024) Integration of High-k STO with Novel GaN High Voltage Transistors
Wisconsin MRSEC researchers have designed and fabricated a new dual-gate 1200 V GaN based bidirectional transistor with good performance. However, performance is limited by failure of the electrically insulating layer, which is currently amorphous silicon nitride (SiN), a conventional material. In the next generation of devices, the team has replaced SiN with a crystalline strontium titanate membrane (SrTiO3) developed by MRSEC IRG 2. SrTiO3 is a much better insulator, so the team expects record performance in ongoing device testing.
(2024) Tuning the Magnetic Anisotropy in Artificially Layered Mn3GaN/Mn3Ga Superlattices
Wisconsin MRSEC researchers have create an artificially magnetic material by alternating layers of Mn3GaN and Mn3Ga in perfect atomic registry with one another. The resulting material offers best-of-both worlds performance for advanced electronic devices based on spin. Their magnetism is easy to switch to encode information, but it is stable once set to a specific state. These outstanding properties arise both from the properties of the layers themselves and from the unique atomic environments that exist where the two layers meet. As a result, combining materials this way lets materials scientists design materials that cannot otherwise exist.
(2024) Graph Machine Learning for Polycrystals
Polycrystalline materials are everywhere in everyday life, but their microstructure – the arrangement of atoms into crystal grains and grains into a piece of material – covers 10 orders of magnitude in size and involves millions important features. This complexity makes it extremely difficult for scientists to predict the properties of polycrystalline materials quickly and accurately. Wisconsin MRSEC researchers have leveraged the power of machine learning to tame the complexity of polycrystalline materials and predict their properties. They have developed a graph neural network approach that predicts materials properties with >98% accuracy 90,000 times faster than competing methods. They applied this model to predict magnetostriction, which quantifies the size change of a material induced by a magnetic field. Development and design of high magnetostriction materials will enable MRSEC researchers to efficiently control magnetism using mechanical force and enable future technologies such like magnetic soft robots