New tools for static and dynamic imaging of antiferromagnetic textures using Bragg diffraction of coherent x rays

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

Non-Technical Abstract Magnetic materials are extensively utilized in modern society in a wide variety of fields, ranging from energy generation to transportation to microelectronic devices. Antiferromagnets are the magnets in which the magnetism exists locally but cancels out on a macroscopic scale. Recently, it was realized that antiferromagnets can be used as media for novel electronic devices with enhanced operational characteristics. These materials also exhibit exotic quantum properties of fundamental scientific interest. Some of these properties may find applications in future quantum information technologies. A fundamental property of any magnet is the formation of small uniform spatial regions called domains. These domains are essential for the operation of magneto-electronic devices, especially for information storage. To understand the quantum properties of antiferromagnets, and to ensure the correct operation of devices based on them, it is essential to image the domains. Time-resolved imaging is of a special importance. Imaging antiferromagnetic domains is difficult. In this project, a novel imaging technique using the x-rays produced by synchrotrons is utilized to investigate the static and dynamic behavior of the domains in antiferromagnets relevant to the studies of quantum matter, and to prospective electronics applications. The technique is uniquely suitable for many domain types previously inaccessible to imaging, especially to time-resolved imaging. The aim is to understand how these materials behave on the microscopic level, and how to control them. In the long term, such studies are expected to contribute towards the better understanding of quantum matter, to the development of faster and smaller electronic devices, and perhaps even to novel quantum information technologies. The proposed work will be carried out at large-scale National synchrotron research facilities. There is a recognized need for young specialists in modern synchrotron x-ray scattering techniques. Such specialists will be trained under this project, contributing to the fulfillment of this long-standing national need. Technical Abstract This Project utilizes a new method of imaging antiferromagnetic (AFM) domain walls and AFM domain textures. The method is based on interference effects in the reflected coherent x-ray beam under the condition of resonant magnetic Bragg scattering. It produces real-space images in a single exposure, without any need for image reconstruction procedures. Its unique capabilities include direct real-space imaging of AFM phase domains, and real-space studies of the AFM domain dynamics on millisecond to hours timescales. The project aims at the demonstration and development of these and several other capabilities of the new imaging method. It will be applied to study AFM domain textures and their dynamics in several systems of high current interest. These systems include magnets with topological AFM domain textures (vortices and skyrmions), compounds utilized in AFM spintronics, including topological AFM spintronics, and multiferroics. This technique should provide valuable means for the characterization of active AFM media in device-like structures utilized both in applied and fundamental science studies. This should be relevant, for example, for the investigations of the exotic Hall-type effects in antiferromagnets, such as at the AFM anomalous Hall effect, the topological Hall effect, etc. For AFM spintronics device engineering, understanding the domain dynamics is key for ensuring device stability and high operation speed. Dynamic studies of the prototype AFM device media will therefore be carried out. Exploratory in-situ studies of the AFM domain control methods relevant to spintronics applications will also be performed. 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.