Major Graphene Breakthrough: Magnet-Free Spin Currents Could Supercharge Quantum Computing

Scientists at TU Delft have unlocked a key quantum effect in graphene without using any magnetic fields, paving the way for ultra-thin quantum circuits.

By layering graphene on a special magnetic crystal, they created stable spin currents that travel along the edges of the material. These currents carry information through the electron’s spin—a feature that could power faster, more energy-efficient electronics and revolutionize quantum computing. This magnet-free approach makes it possible to build powerful spintronic devices small enough to fit inside next-generation chips.

Magnet-Free Quantum Spin Hall Breakthrough

Quantum physicist Talieh Ghiasi has just shown that graphene can host the quantum spin Hall (QSH) effect without any external magnets. In this state, electrons glide effortlessly along the material’s edges while all their spins point the same way.

“Spin is a quantum mechanical property of electrons, which is like a tiny magnet carried by the electrons, pointing up or down,” Ghiasi explains. “We can leverage the spin of electrons to transfer and process information in so-called spintronics devices. Such circuits hold promise for next-generation technologies, including faster and more energy-efficient electronics, quantum computing, and advanced memory devices.”

Integrating Spintronics On-Chip

Until now, researchers needed bulky magnetic fields to detect spin currents in graphene—an approach that would never fit inside everyday electronics.

“In particular, the detection of quantum spin currents in graphene has always required large magnetic fields that are practically impossible to integrate on-chip. Thus, the fact that we are now achieving the quantum spin currents without the need for external magnetic fields opens the path for the future applications of these quantum spintronic devices,” says Ghiasi.

The scientists from the Van der Zant lab were able to bypass the need for external fields by layering the graphene on top of a magnetic material: CrPS₄. This magnetic layer significantly altered the graphene’s electronic properties, giving rise to the QSH effect in graphene. Ghiasi: “We observed that the spin transport in graphene gets modified by the neighbouring CrPS₄ such that the flow of electrons in graphene becomes dependent on the electrons’ spin direction.”

Topologically Protected Spin Signals

The quantum spin currents that the scientists detect in the graphene-CrPS₄ stack are ‘topologically’ protected, implying that the spin signal travels stays intact over tens of micrometres long distances without losing the spin information in the circuit. “These topologically-protected spin currents are robust against disorders and defects, making them reliable even in imperfect conditions,” Ghiasi says. Preserving spin signal without any loss of information is vital for building spintronic circuits.

Path to Ultra-Thin Quantum Circuits

This discovery paves the way toward ultrathin, graphene-based spintronic circuits, promising advancements in next-generation memory and computing technologies. The observed spin currents in graphene offer a powerful new route for efficient and coherent transfer of quantum information through electron spins. These robust spintronic devices could serve as essential building blocks in quantum computing, seamlessly linking qubits together within quantum circuits.

Reference: “Quantum spin Hall effect in magnetic graphene” by Talieh S. Ghiasi, Davit Petrosyan, Josep Ingla-Aynés, Tristan Bras, Kenji Watanabe, Takashi Taniguchi, Samuel Mañas-Valero, Eugenio Coronado, Klaus Zollner, Jaroslav Fabian, Philip Kim and Herre S. J. van der Zant, 24 June 2025, Nature Communications.
DOI: 10.1038/s41467-025-60377-1

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