Researchers achieve electrical control of spin currents in graphene via ferroelectric switching

A collaborative European research team led by physicists from Slovak Academy of Sciences has theorized a new approach to control spin currents in graphene by coupling it to a ferroelectric In₂Se₃ Monolayer. Using first-principles and tight-binding simulations, the researcher showed that the ferroelectric switching of In₂Se₃ can reverse the direction of the spin current in graphene acting as an electrical spin switch. This discovery  offer novel pathway toward energy-efficient, nonvolatile, and magnet-free spintronic devices, marking a key step toward the fabrication of next-generation spin-based logic and memory systems.to control spin textures

Over the past two decades, spintronics has emerged as one of the most promising frontiers in nanoelectronics, seeking to exploit the intrinsic angular momentum, or spin, of electrons to carry and process information. Unlike conventional charge-based electronics, spin-based logic and memory promise orders-of-magnitude reductions in power consumption and heat dissipation, along with faster operation speeds and nonvolatile data retention.

Despite rapid progress in materials and device architecture, a fundamental obstacle persists: achieving precise, low-energy electrical control over spin currents without relying on external magnetic fields. Magnetic manipulation, although effective, poses major challenges for device scalability, energy efficiency, and compatibility with existing semiconductor technologies.

In this context, two-dimensional (2D) materials have opened a new landscape where graphene is one of the most popular representative.

Graphene, with its exceptional electronic mobility and long spin-relaxation time, is a prime candidate for spintronics. However, its weak intrinsic spin-orbit coupling limits direct spin control. To overcome this, researchers have turned to van der Waals heterostructures, stacking graphene with other 2D materials to induce new functionalities through proximity effects.

One attractive heterostructure involves coupling of graphene to ferroelectric materials with a spontaneous electric polarization that can be controlled by an applied voltage. When a ferroelectric material is brough in contact to graphene, its electric dipole can break inversion symmetry at the interface. This proximity can, in principle, allow the spin orientation and the pure electric switching.

Taking this concept into consideration, a group of researchers introduced a novel graphene/In₂Se₃ heterostructure platform where proximity effects induced by the ferroelectric polarization of In₂Se₃ can modulate the spin-orbit coupling in graphene. Using first-principles calculations and tight-binding modeling, they showed that flipping the polarization direction of In₂Se₃ reverses the sign of the Rashba-Edelstein effect thereby switching the chirality of spin textures and the spin current direction. This modulation occurs without magnetic fields and with negligible power once the polarization is set. 

The research team investigated graphene/In₂Se₃ heterostructures at two configurations: a perfectly aligned (0°) interface and a twisted geometry (17.5°). Through detailed electronic structure calculations, they found that reversing the ferroelectric polarization of the In₂Se₃ monolayer reverses the sign of the charge-to-spin conversion coefficient, acting as an electrical “chirality switch” for spin currents in graphene. At zero twist, the system exhibits a conventional Rashba-Edelstein effect (REE), where an applied charge current generates a transverse spin accumulation whose direction is locked to the ferroelectric polarization. At 17.5°, the system transitions into a regime dominated by an unconventional Rashba-Edelstein effect (UREE), in which the spin current becomes nearly collinear with the charge flow due to the emergence of a radial Rashba field, a novel phenomenon previously inaccessible in planar graphene systems.

Their results provide a theoretical foundation for realizing graphene-based spin transistors controlled by ferroelectric switching, potentially enabling next-generation spin logic and memory devices with low energy consumption and high speed. The study underscores the promise of integrating two-dimensional ferroelectric materials with graphene to harness novel spintronic functionalities.

Future efforts should focus on the experimental validation of the proposed results to fully realize electrically controlled, non-volatile spintronic devices with low energy consumption and high speed.

The research has been recently published in the online edition of Materials Futures, a prominent international journal in the field of interdisciplinary materials science research.

Reference: Marko Milivojević, Juraj Mnich, Paulina Jureczko, Marcin Kurpas, Martin Gmitra. Ferroelectric switching control of spin current in graphene proximitized by In₂Se₃[J]. Materials Futures. DOI: 10.1088/2752-5724/ae18ea