CAREER: Multiferroicity in van der Waals Heterostructures

University Of Maryland, College Park, College Park MD

Investigators

Abstract

Nontechnical description: Ferromagnetic and ferroelectric materials can be used to build novel quantum devices, utilizing their magnetic properties even in absence of external fields. When ferromagnetic and ferroelectric materials are integrated together, forming the so-called “multiferroics”, the material functions are largely enhanced beyond the simple combination of two materials, leading to novel magnetoelectric phenomena. Especially when these materials are atomically thin, their interactions become even more exotic. The emerging ferromagnetic and ferroelectric materials provide intriguing building blocks for layer-by-layer assembling of novel multiferroic heterostructures. Understanding the fundamental magnetoelectric physics underlying the multiferroicity in such heterostructures and thereby developing effective approaches to manipulate the multiferroicity, have foundational significance for advancing these emerging heterostructures for ultracompact, energy-efficient spintronic devices. This project studies the effects of electrostatic doping, electric field, interfacial chemistry, and lattice strain on the resultant multiferroicity, potentially leading to the development of engineering approaches to advance human control of the new class of functional heterostructures. Students of various levels, including graduate, undergraduate, and high-school students, from all backgrounds, are trained with a broad range of expertise in 2D heterostructure assembling, nanodevice fabrication, cryogenic hardware manufacturing and operation, and a variety of microscopies and spectroscopies. This project can help strengthen the future workforce for the quantum information science and technologies in the U.S. and raise the public literacy of quantum technologies by the development of new course materials and local and regional educational activities. Technical description: The recently emerged ferromagnetic and ferroelectric 2D vdW materials are atomically thin crystals with long-range ferroic orders, providing ideal condense matter platforms for exploring the low-dimensional spin and dipole physics. When 2D ferromagnets and 2D ferroelectrics are integrated to form multiferroic heterostructures, the interplay between the disparate ferroic orders can generate a plethora of emergent magnetoelectric phenomena, potentially leading to novel low-power spintronic devices. The research objective of this project is to elucidate the fundamental mechanisms underlying the magnetoelectric multiferroicity in vdW heterostructures, including charge transfer induced doping, built-in electric field, interfacial hybridization, and piezoelectric strain effect. Given these factors are ubiquitous in heterostructure systems, understanding their roles in the resultant multiferroicity can provide critical insights for designing functional vdW heterostructures, which potentially transforms the landscape of ferroic quantum heterostructures and enabling disruptive spintronic and quantum technologies. Based on these fundamental understandings, effective engineering approaches can be developed to create heterostructures with desirable magnetoelectric physical properties. The main research approaches include assembling various types of vdW multiferroic heterostructures and fabricating these heterostructures based devices, which are further engineered by electrostatic doping, electric field, and piezoelectric strain. The resultant physical properties are probed by a range of microscopies and spectroscopies 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.