Synopsis

# Chiral Magnetism Under Electric Control

Physics 10, s117
An applied electric field can be used to control a twisted form of magnetic ordering inside small domains of multiferroic materials.

Magnetic ordering usually involves a parallel or antiparallel alignment of spins, but in some cases it is characterized by a spiraling pattern. This so-called chiral magnetism might one day prove useful for high-density data storage. Researchers have now demonstrated that electric fields can switch the magnetic chirality of multiferroics—materials that are both ferroelectric and magnetic. The experiments were performed at temperatures in which long-range correlations in the magnetic ordering were absent. This implies that chiral magnetism could be controlled within small domains that could store a single bit of information.

Multiferroics exhibit long-range chiral magnetic ordering when cooled below a critical temperature. Recent work has shown that applying an external electric field while cooling below this critical temperature can fix the orientation (clockwise vs counterclockwise) of the magnetic chirality. This electric control, however, works only on large, fully ordered samples and not on small domains that would allow dense packing of data.

To explore electric control without long-range order, Jonas Stein from the University of Cologne, Germany, and his colleagues performed polarized neutron scattering on two multiferroics: ${\text{TbMnO}}_{3}$ and ${\text{MnWO}}_{4}$. By measuring the flipping of the spins of neutrons scattered by the samples, the researchers extracted information about the magnetic ordering in the material. They found that an applied electric field could locally induce chiral magnetism even when the temperature was above the critical temperature, that is, when the sample was too warm for the long-range order to be frozen in. This suggests that electric control could work on small, individual domains, without requiring long-range ordering. Besides showing the potential for data storage, the experiments also highlight the role of excitations, called electromagnons, in establishing long-range order in multiferroics.

This research is published in Physical Review Letters.

–Michael Schirber

Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.

## Related Articles

Interdisciplinary Physics

### Sustainable Plastics Inspired by Nature

Plant-based plastics offer a sustainable alternative to traditional petrochemical plastics. Scientists and engineers are making the shift easier by fine-tuning the structure and function of these biomaterials while also developing better processing techniques. Read More »

Condensed Matter Physics

### A Twist in Topological Wisdom

New theoretical predictions overthrow the assumption that a material’s bulk topological properties are linked to the same properties at its surface.  Read More »

Condensed Matter Physics

### The Rich Inner Life of the Hydrogen Chain

A one-dimensional chain of hydrogen atoms displays a wide variety of many-body effects—suggesting that the chain can be a useful model system for condensed-matter physics. Read More »