An electric current controls a Hall response in a magnetic material
· BehindLines newsroom
Researchers at Tohoku University and the Japan Atomic Energy Agency (JAEA) have electrically controlled a quantum response in a magnetic material. Their November 5 announcements describe a study published in Newton on November 4, by the American date. The demonstration uses crystalline thin films of Mn₃Sn, a manganese–tin compound.
The experiment measures a voltage transverse to the current. At room temperature, the nonlinear component under study varies with the cube of the current: the researchers describe a third-order nonlinear Hall effect. This relationship is the feature being examined, rather than a simple proportional increase between the two quantities.
Reversing the response’s sign
The material has chiral antiferromagnetic order. Measurements and calculations connect its electrical response with the arrangement of spins and the quantum geometry of electronic states. Quantum geometry describes geometric properties of the electrons’ quantum states.
To influence the system, the team also uses a neighbouring heavy-metal layer. A current in that layer produces a spin–orbit torque that acts on the magnetic order. Pulses with opposite polarities can thereby reverse the sign of the Hall response.
This result provides a way to control the observed response. The measured effect changes sign; describing it only as a switch turning a current on or off would lose the substance of the experiment.
Possible electronic functions
The teams point to potential uses in nonlinear signal processing, including frequency conversion, rectification and amplification. These are prospects: the announcements demonstrate neither an industrial component nor a quantified improvement in speed or energy consumption.
The JAEA still lists reducing the required current and improving efficiency among its objectives. Both institutions are reporting the same research. Their accounts corroborate each other, but are not two independent reproductions of the experiment.