Epitaxial engineering of layered magnetic pnictides

University Of Notre Dame, Notre Dame IN

Investigators

Abstract

Non-technical Abstract: Efficient high-density data storage technology relies on our ability to sense and manipulate electrons. The past decade witnessed the discovery the magnetic topological insulators, a class of materials where the spin of electrons is locked to the direction of their motion. This property has been exploited to design efficient data storage devices utilizing unique magnetic properties. The project aims to design, synthesize and study a new class of topological materials, where the interaction of magnetism with electrons enables new electrical and optical properties. These properties can become the foundation for new means of sensing information that can be exploited in next-generation optical detectors and novel devices. The research activities under this project support the training of graduate, undergraduate and high school students to acquire highly sought-after skills needed to advance the materials and semiconductor workforce of the future. The findings stemming from those research activities are disseminated to a non-expert audience through public library of activities and through social media outreach. Technical Abstract: Layered magnetic pnictides from the EuX2(As,P)2 family (X=In, Mn) are antiferromagnets that can either be topological (X=In) or correlated (X=Mn) insulators. They have recently been studied as single crystals but have yet to be grown as wafer-scale films, necessary for a variety of measurements and applications. This project employs molecular beam epitaxy to achieve the synthesis of thin films of layered magnetic pnictides. Using knobs enabled by epitaxial synthesis, the research team aims to carry out a systematic tuning of the magnetic and electronic properties of these materials. An initial research activity examines how chemical alloying, strain and quantum confinement impact the helimagnetic state of EuIn2As2 and its electronic properties. A specific type of alloying with Mn on the In site is sought to bring a topological and a correlated state into coexistence. A second activity aims to identify manifestations of Berry curvature and quantum geometric phases in the resonant infrared response of EuX2(As,P)2 films through magnetooptical and photovoltaic measurements. Lastly, the project aims to search for a quantized anomalous Hall state by electrically gating EuIn2As2¬ films engineered to be insulating in the bulk. The project synergizes these research tasks with a strong educational component that includes the training of graduate, undergraduate and high school students on tools that are valuable to quantum material science and the semiconductor industry. One of those researchers is recruited from a neighboring women’s college and participates in experiments on site and at user facilities. The findings and discoveries made through this project are partly disseminated to the general public through public library lectures and social media broadcasts. 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.