Altermagnetoelectric Spin Field Effect Transistor Enables Electric Field Control of Spin for Low-Power Electronics

Spin field-effect transistors represent a potential pathway to dramatically reduce energy consumption in future electronics, but current designs face limitations in both material selection and the distance over which spin information can travel. Ziye Zhu, Xianzhang Chen, and Xunkai Duan, alongside Zhou Cui, Jiayong Zhang, and Igor Zutic, now present a fundamentally different approach to SFET operation, one that leverages the unique properties of multiferroic altermagnets. Their work demonstrates that electric fields can control spin splitting through symmetry, rather than relying on conventional spin-orbit physics, creating clear on and off states in a transistor. Crucially, the researchers overcome a major obstacle in multiferroic device design by successfully imprinting multiferroic altermagnetism into highly conductive materials, paving the way for practical SFET implementation and establishing a versatile platform for advanced spintronic technologies.

Spin field-effect transistors (SFETs) represent promising candidates for low-power spintronic devices, but existing designs face limitations due to restricted material choices and short spin-coherence lengths. This research proposes a new operating principle based on multiferroic altermagnets, where electric fields control spin splitting through symmetry control, rather than conventional spin-orbit physics. The team employs effective modeling combined with quantum transport simulations to demonstrate that conductance depends on the degree of matching between the electrically controlled spin texture of the channel and the fixed spin polarization of the ferromagnetic contacts, offering a pathway to overcome the material and coherence length constraints of traditional spin-based devices.

Altermagnetism, Multiferroicity and Complex Couplings

This research comprehensively investigates altermagnetism, a relatively new form of magnetism, and its interplay with multiferroicity, the coexistence of multiple ferroic orders. The work explores the fundamental physics, materials discovery, and potential device applications of this exciting field, extending beyond simple coexistence to delve into complex couplings, symmetry considerations, and novel phenomena. Investigations focus on foundational work on altermagnetic multiferroics and the almagnetoelectric effect, alongside theoretical background for understanding electron transport in materials crucial for device applications. Numerous materials, including VOI2, BiFeO3, and various 2D materials like WSe2 and WSeTe, are investigated as potential altermagnetic multiferroics.

The research explores how crystal structure, symmetry, and electronic properties influence the emergence of altermagnetism and multiferroicity, with a strong emphasis on 2D materials due to their unique properties and potential for novel devices. Theoretical modeling relies heavily on first-principles calculations using density functional theory (DFT) to investigate the electronic structure and magnetic properties of materials, alongside the development of simplified models to understand complex interactions. Transport calculations predict the behavior of electrons in altermagnetic materials. A central theme is the almagnetoelectric effect, exploring the coupling between magnetic and electric orders.

The research also investigates ferroelastic altermagnetism, the interplay between altermagnetism and structural deformation, and classifies different types of multiferroic behavior based on coupling mechanisms. Symmetry-locked magnetoelectric coupling and odd-parity magnetism are also explored. This interdisciplinary research, drawing on condensed matter physics, materials science, and device physics, places this work at the forefront of materials science with a strong computational component.

Graphene Spin Splitting via Altermagnetic Proximity

Scientists have achieved a breakthrough in spintronic device design with the development of the altermagnetoelectric spin field-effect transistor (AMSFET), a novel device that utilizes multiferroic altermagnets to control spin transport electrically. This work addresses the challenge of reconciling the need for metallic channels with the typically insulating nature of materials exhibiting ferroelectricity. Researchers demonstrate that by transferring multiferroic altermagnetic order into highly conductive channels via the proximity effect, they can create functional spintronic devices. First-principles calculations performed on graphene placed on multiferroic vanadium sulfide halides confirm that graphene acquires a ferroelectrically switchable spin splitting while retaining its metallic character, a crucial step towards practical device implementation.

The AMSFET operates on the principle of symmetry-mediated locking between ferroelectric polarization and altermagnetic spin texture, enabling fully electrical control of spin transport and distinct high- and low-conductance states. The team modeled the device with a three-terminal configuration, utilizing ferromagnetic source and drain electrodes and a multiferroic altermagnet channel, demonstrating the universality and robustness of this operating principle through quantum-transport simulations. These materials enable the control of spin-dependent transmission, allowing for the creation of distinct conductance states and paving the way for next-generation spintronic devices. This research establishes a viable route for AMSFET implementation and identifies multiferroic altermagnets as a new class of channel materials for spintronics.

Multiferroic Control of Spin Texture Alignment

This research establishes a novel approach to spin field-effect transistors, moving beyond traditional designs reliant on limited materials and short spin coherence. Scientists demonstrate that multiferroic altermagnets offer a promising alternative, enabling electrical control of spin through symmetry rather than spin-orbit coupling. Through effective modeling and quantum transport simulations, the team reveals that device conductance is determined by the alignment between electrically controlled spin textures and fixed spin polarization in the contacts, creating distinct ON and OFF states. Researchers successfully imprinted multiferroic altermagnetism into highly conductive materials via the proximity effect, confirmed through first-principles calculations on vanadium sulfide halides. These calculations demonstrate the creation of a switchable spin splitting while maintaining metallic conductivity, paving the way for practical SFET implementation and identifying multiferroic altermagnets as a versatile platform for future spintronic devices.