Scientists unravel the mystery of the physics of the “Hall effect” through the study of Weyl antiferromagnets
Study Figure 1 – Mn₃Sn Antichiral Magnetic Structure / Magnetization Piezoelectric Control
On the one hand, the ferromagnets in the traditional magnetic memory need to avoid the mutual interference of adjacent data bits, so it is difficult to achieve more dense packaging.
On the other hand, by using the Hall Effect discovered by Edwin Hall in 1879, it is possible to apply a voltage perpendicular to the current direction on the antiferromagnetic material.
Figure 2 – Piezomagnetic effect of topological diamagnet Mn₃Sn under in-plane uniaxial compression
When all the spins in the diamagnet are flipped, the sign of the Hall voltage also changes at any time — thus representing the “0” or “1” value of a binary bit, respectively.
Embarrassingly, although scientists have long known about the Hall effect in ferromagnetic materials, its effect in antiferromagnets was only recently recognized and poorly understood.
Study Figure 3 – AHE of Weyl Antiferromagnets / Sign Inversion under In-Plane Uniaxial Strain
The good news is that a joint research team from the University of Tokyo in Japan, Cornell University in the United States, Johns Hopkins University in the United States, and the University of Birmingham in the United Kingdom has just released the latest results on the “Hall effect” in Weyl antiferromagnets (Mn₃Sn). explain.
It is reported that the material has a particularly strong spontaneous Hall effect. The new paper recently published in the journal “Nature Physics” has not only had a profound impact on the field of ferromagnet/antiferromagnet research, but also triggered our new thinking on the next generation of storage devices.
Study Figure 4 – Different Strain Control of Hall Vector K in ferrohalic, parahallic and diahallic states
As a “Weyl semimetal”, Mn₃Sn is not a completebeautifulAntiferromagnet, and it has a weak external magnetic field. On this basis, the researchers tried to figure out whether the Hall effect is caused by this weak magnetic field.
During the experiments, the scientists used a device designed by study co-author Dr Clifford Hicks from the University of Birmingham – which can be used to apply variable stress to the material being measured.
Extended Data Figure – 1: Piezoelectric switching of anomalous Hall effect in an antiferromagnet at room temperature
By applying this stress to the Weyl antiferromagnet, the residual external magnetic field is increased. If the Hall effect is driven by a magnetic field, the voltage across the material will have a corresponding effect.
However, it turned out that the voltage did not change substantially, proving that the magnetic field did not play an important role. Instead, the study came to the conclusion that the arrangement of spintronics within the material is the main cause of the Hall effect.
“The experimental demonstration that the Hall effect is caused by the quantum interaction of conduction electrons with their spin electrons is crucial for our understanding and improvement of magnetic storage technology,” said Clifford Hicks.
For more information on this study, please also go toNature Physics“View, the original title is “Piezomagnetic switching of the anomalous Hall effect in an antiferromagnet at room temperature”.