Nanoscale Magnetic and Electronic Heterostructures

Our group explores the behavior of nanoscale magnetic, electronic, and superconducting heterostructures in 2D and 3D, novel materials for microelectronics and neuromorphic computing, and energy storage materials.

We seek to develop a framework to design, explore, and control the emergent behavior in functional nanoscale heterostructures and deepen our understanding of the complex energy landscape that governs such behavior. Our focus is on confined heterostructures of nanomagnetic materials comprising ferromagnets and antiferromagnets. We aim to design and understand the formation of novel spin textures and their transport properties by controlling the ferroic interactions using (i) geometric parameters, such as patterned shapes, curvature, and interfaces, and (ii) microstructural parameters, such as defects, strain, and coupling between adjacent nanostructures. The specific challenges that we are addressing include:

The effect of geometric confinement and curvature on spin textures in 2D and 3D nanostructures
Emergent topological spin textures and their collective behavior in mixed-dimensional van der Waals (vdW) ferromagnetic heterostructures
Magnetic frustration and solitonic transport in artificial spin ice networks
Driven dynamics of magnetic nanostructures
Domain behavior and transport in synthetic antiferromagnets

Our group also works on exploring novel materials that exhibit resistive switching phenomena for synaptic computing elements that can enable highly efficient neuromorphic computing architectures. These materials include quantum materials showing charge density waves, as well as ferroelectric materials. We seek to understand the underlying atomic and electronic phenomena using our extensive expertise in materials synthesis and in-operando experiments.

In addition, our group works in the field of quantum magnonics and explores how magnetic materials, such as magnetic crystals and thin film devices, can be incorporated and applied in quantum information science, by developing state-of-the-art hybrid magnonic systems with coplanar superconducting resonator circuits. The goal is to understand coherent interactions of magnons down to the single quantum level and to explore the potential of magnetic systems for supplemental functionalities in quantum information science, such as microwave-to-optic transduction and chip-embedded nonreciprocity.

Our research approach utilizes in-situ 2D and 3D microscopy to visualize and understand the nanoscale behavior. We use a combination of aberration-corrected Lorentz transmission electron microscopy, advanced scanning force microscopy, and magneto-optic Kerr effect microscopy in order to address scientific challenges. We have developed in-situ techniques that allow us to visualize domain behavior, local structural and electronic environment, and transport behavior in nanostructures as a function of external stimuli, such as applied fields, temperature, and time. We are also developing novel capabilities such as voltage-triggered ultrafast electron microscopy to image dynamic processes in magnetic and electronic materials. We combine these experiments with simulations and measurement of charge, potential, and current at the mesoscopic length scale. The research on quantum magnonics utilizes the triple-axis cryogenic electromagnet and Bluefors dilution refrigerator for cryogenic microwave measurements down to 10 mK and with magnetic fields up to 1 T in-plane and 9 T out-of-plane. We also apply the microscopy and electronic transport measurement techniques to explore materials for applications in microelectronics, solid oxide fuel cells, ferroelectric memory, and quantum information science.

More broadly, we interact with the wider imaging community at Argonne to develop experimental and computational capabilities for multi-modal imaging at the nanoscale, including incorporating machine learning approaches.