Combining semiconductor functionality with controllable magnetism is a longstanding goal in spintronics. Conventional electronics manipulate the charge of electrons, while spintronics seeks to additionally use their spin to store and process information, potentially enabling new forms of low-power logic and memory. A key challenge, however, is finding materials that combine robust magnetic order with the electrical tunability of a semiconductor.
A team led by Ass. Prof. Ahmet Avsar from the Department of Materials Science and Engineering at the National University of Singapore has now demonstrated an air-stable two-dimensional semiconductor in which magnetism can be introduced through dilute atomic doping and subsequently controlled using an electric field. The work, led by PhD student Qi Zhang, was published in Science Advances under the title “Electrical control of induced magnetism in an air-stable two-dimensional semiconductor.”
The study starts from PtSe2, an air-stable 2D material that changes from metallic to semiconducting as its thickness is reduced below six layers. Introducing a small concentration of Fe atoms (~1%) adds magnetism while preserving this thickness-dependent electronic behaviour. Atomic-resolution microscopy confirms that Fe substitutes directly into the PtSe2 lattice without detectable clustering or phase segregation.
Reducing the thickness and carrier concentration transforms the same material from a ferromagnetic metal into an antiferromagnetic semiconductor. Bulk Fe-doped PtSe2 is ferromagnetic up to approximately 320 K, above room temperature, with ferromagnetic signatures persisting into the metallic few-layer regime. In thinner semiconducting devices, antiferromagnetic order instead emerges, reaching approximately 105 K.
Most importantly, in the 2D semiconducting regime, the magnetism becomes electrically tunable. Applying a gate voltage changes the carrier concentration and strongly modifies the antiferromagnetic order. In semiconducting devices, the magnetic hysteresis can be switched ON and OFF electrically, demonstrating a gate-tunable 2D dilute magnetic semiconductor.
“What makes this system particularly interesting is that we start from an air-stable, nonmagnetic semiconductor, introduce magnetism, and then control that magnetism electrically,” said Assistant Professor Avsar. “This combination is exactly what we have been looking for in dilute magnetic semiconductors.”
Calculations reveal that this evolution originates from competing magnetic interactions. At high carrier concentrations, carrier-mediated RKKY interactions favour ferromagnetism. As the carrier concentration decreases in the semiconducting regime, superexchange becomes increasingly important and stabilizes antiferromagnetic order.
The work also builds on Qi Zhang’s recent ACS Nano study showing that transition-metal doping can strongly modify the electronic properties and semiconductor-to-metal transition of PtSe2. Exploring other transition-metal dopants could provide access to different magnetic interactions and spin-dependent electronic states. An important next goal is to identify dopants that can extend robust magnetic order to room temperature in the electrically tunable 2D semiconducting regime, as predicted theoretically.
Reference
Q. Zhang, M. Ghosh, Y. Zhumagulov, O. Cicvárek, Y. Chen, F. Long, Y. Lin, A. Mejamai, J. Félisaz, I. Plutnarova, S. Zhou, M. Bosman, G. Eda, O. V. Yazyev, Z. Sofer, A. Avsar*, “Electrical Control of Induced Magnetism in a Two-Dimensional Semiconductor”, Science Advances 12, eaeb0659 (2026).
