EPSCoR Research Fellows: NSF:Resonant X-ray Studies of Magnetic Structures and Excitations in the Two-Dimensional Limit

In magnetic materials, the particular microscopic pattern of magnetic ordering is determined by interactions between the materials constituent magnetic moments and can have profound effect on the material properties. A special class of magnetic materials, called frustrated magnets, have magnetic interactions that cannot be mutually satisfied. Such competing magnetic interactions generate exotic magnetic structures that often have the special property that they do not exhibit a net magnetic field, but can still influence electric or thermal currents.

This unique characteristic makes frustrated magnets ideal to realize future low energy dissipation spintronic devices. However, characterizing the magnetic structures and microscopic energy scales that stabilize those structures in a given material prepared in device relevant geometries remains an outstanding challenge. This project will develop and use advanced synchrotron x-ray scattering techniques at the National Synchrotron Light Source II to elucidate the magnetic structures and fundamental dynamic response characterizing frustrated magnetic materials in nanoscale device relevant configurations.

The material parameters quantified through this work will be essential input into theoretical frameworks for predicting physical properties of model frustrated magnets and provide essential input towards incorporating their novel functionalities into future energy efficient technologies. The project will establish a long term sustainable collaboration between Brookhaven National Laboratory and Brown University to train graduate students in synchrotron x-ray techniques and magnetic materials characterization.

Frustrated van der Waals magnets offer unprecedented opportunities to realize new magnetic phases of matter exhibiting complex, multi-sublattice, magnetic textures. Such magnetic textures may exhibit a vanishing net magnetization and hold great promise for fast and low dissipation spintronic devices because they exhibit a vanishing net magnetization.

However, elucidating the underlying microscopic physics of new and existing materials is challenging because the antiferromagnetic textures span broad length scales, do not couple directly to magnetic fields, and there is a current lack of measurements that can directly probe magnet structures and excitations in the two-dimensional limit. This project will catalyze a long term sustainable collaboration between researchers at Brookhaven National Lab and Brown University to develop new probes of magnetic order and excitations in two-dimensional materials and across nanometer length scales.

Planned work comprises a comprehensive resonant x-ray scattering program to probe the static and dynamic response functions of model frustrated magnets. Resonant inelastic x-ray scattering will be used to quantify the dimensional evolution of dynamic magnetic response functions in a model van der Waals antiferromagnet, exfoliated to the two-dimensional limit.

Resonant elastic x-rays scattering with nano-focused beams will be used to quantify the chiral antiferromagnetic domain distribution in a metallic frustrated magnet, and follow its evolution under applied biasing fields. New tools for quantifying the magnetic response of frustrated antiferromagnets will be developed and used to elucidate their microscopic organizing principles of frustrated magnets and provide essential input for the design of antiferromagnetic spintronics that require precise domain control.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.