Tohoku University and JAEA switch a quantum-geometric nonlinear Hall state in Mn3Sn with current pulses

Researchers at Tohoku University and the Japan Atomic Energy Agency (JAEA) controlled the quantum-geometric nonlinear Hall (QgNLH) state with electric current, according to ResearchSEA. The authors describe this as the first such demonstration. The work was published in the journal Newton on November 4, 2026, and used epitaxial thin films of the chiral antiferromagnet Mn3Sn. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗

In an ordinary conductor, voltage and current are proportional, as described by Ohm's law and the Hall effect. In the nonlinear Hall effect, the transverse Hall voltage departs from this linear relation. Quantum geometry, the geometric structure of electronic quantum states, contributes to such a response. It had been treated as a built-in property of the material, which made control by current difficult. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗

Nonlinear Hall effect in Mn3Sn

The team first observed a third-order nonlinear Hall effect at room temperature, in which the nonlinear voltage is proportional to the cube of the current. Experiments combined with theoretical calculations showed, according to the authors, that the effect has a quantum-geometric origin and is reversible when the spin structure of Mn3Sn is switched. This indicates coupling between the QgNLH state and the spin structure. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗

Switching by spin-orbit torque

For electrical control, the researchers used spintronic methods. Current flowing in a heavy-metal layer adjacent to Mn3Sn produces a spin-orbit torque that acts on the spin structure of Mn3Sn and can switch it. By applying current pulses of opposite polarity, the team switched the sign of the third-order nonlinear Hall response. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗

Lead author Tomohiro Uchimura said that deterministic switching of the QgNLH state can be achieved under a finite bias magnetic field, and fluctuation of the state under zero bias field. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗

The corresponding authors, Jiahao Han and Shunsuke Fukami, said the approach may help develop current-tunable nonlinear devices such as frequency multiplexers and rectifiers. In their view, such devices could benefit from the energy efficiency and speed of magnetoresistive random access memory (MRAM), owing to the spintronic methods used. This is the authors' expectation; the reported measurements were made on a Hall bar device. asiaresearchnews.comResearchSEAasiaresearchnews.comOpen source ↗