Curvilinear multiferroics

Introduction

Disruptive development of brain-inspired computing, machine learning, and deep neural networks for electronic assistants in smartphones, autonomous driving systems, or ChatGPT requires new logic and storage concepts, which are beyond conventional von Neumann computer architectures.

Key Enablers

Materials known as multiferroics are identified as key enablers of these technologies. In contrast to ferromagnets, where the magnetic state is controlled by magnetic fields (energy inefficient due to flowing currents), magnetoelectric multiferroics allow manipulation of magnetic states by electric fields.

Challenges with Current Materials

The great promise of multiferroic materials towards energy-efficient computing is compromised by the limited material portfolio. Literally, after decades of research, we have only one multiferroic (i.e., BiFeO3) potentially promising for room temperature spintronic devices. Even this most advanced material meets challenges outperforming state-of-the-art CMOS elements.

Current Design Approaches

The mainstream approach to design magnetoelectrics is to induce ferroelectric ordering in magnets to control non-volatile magnetic states electrically. Although intuitively understandable, this concept has failed to provide a technologically relevant multiferroic.

Proposed Paradigm Shift

Here, we propose a paradigm shift in the design of multiferroic materials. Instead of trying to induce ferroelectricity, we will realize curvilinear multiferroics by imposing ferrotoroidal order in geometrically curved magnetic thin films.

Predictions and Implications

Fundamentally, we predict that effects of geometric curvature and inhomogeneous mechanical strain will induce a sizeable ferrotoroidal order parameter in any magnetically ordered material, rendering this material multiferroic. Hence, curvilinear systems will turn rare ferrotoroidic materials into a broadly populated material class, available for material science and technologies similar to conventional ferromagnets.

Project Goals

This project will enable curvilinear multiferroics and validate their application potential for memory and logic devices.