EPSCoR Research Fellows: NSF: Neutron Scattering Experiments on Magnetic Weyl Semimetals

“Topological” materials have attracted attention due to their potential uses in next generation technologies. In these materials, the details of how their atoms are arranged in space and how any magnetic atoms are arranged plays a central role in whether interesting properties are present. A powerful method for determining these arrangements is an experimental technique called neutron scattering (NS).

NS experiments take place at large facilities, such as the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Newer sources like the SNS use modern computing and data storage capabilities to record large amounts of information about each neutron that is measured in an experiment, which encodes information about the material being studied.

To exploit this information, one must use analysis techniques that are different from those used at older NS facilities. This project enables the PI to learn these techniques. The PI and his lab will construct a probe that will continuously change the electric field that their topological samples see during an NS experiment.

Analyzing NS experiments done with a changing field are only possible by exploiting this additional data with new techniques. As technology literacy is increasingly important in all aspects of life, a lack of training is a pressing issue in the state of Kentucky. The state-of-the-art analysis and probe construction proposed here will help address this issue.

Recent developments in neutron scattering (NS) data collection and analysis can lead to new opportunities at the latest generation neutron sources such as the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). These facilities harness modern computing power to collect data using a paradigm called “event mode” detection. When a neutron is scattered from a sample into a detector, each neutron is recorded individually along with all information about the detection.

One area where event mode detection can prove useful is in the study of Weyl semimetals. Weyl semimetals are naturally conductors in their bulk, allowing exploitation of both protected surface states and more conventional bulk conducting states. This proposal is to learn new analysis techniques to increase the information that can be taken from NS experiments on the crystalline and magnetic properties of such materials by taking advantage of the event mode data generated at modern neutron sources such as the SNS.

The PI will work closely with scientists at ORNL to learn how to exploit event mode analysis on existing data and construct a probe to apply an electric field at cryogenic temperatures to samples in NS experiments. This will enable experiments that continuously tune the Fermi level and observe how ordered magnetic states in magnetic Weyl materials are affected by the changing field.

Novel correlated electron states such as those studied in this proposal have the potential to make a sea change in future technologies.

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.