Physicists discover 'magnetotoroidic effect'

September 26, 2011 by Lisa Zyga, feature

( -- For many years, scientists have known about the magnetoelectric effect, in which an electric field can induce and control a magnetic field, and vice versa. In this effect, the electric field has always been homogeneous. Now, scientists have found that a curled electric field can also be used to control magnetic fields, constituting a novel phenomenon that they call the "magnetotoroidic effect."

“A homogeneous electric field is one in which the electric field is a constant everywhere, as that produced by opposite static charges on two metallic capacitor plates,” Wei Ren of the University of Arkansas told “On the other hand, a time-varying can also induce an electric field that possesses a curl according to the Maxwell-Faraday equation. However, such a curl is zero in the homogeneous electric field.”

In their study, Ren and coauthor L. Bellaiche, also from the University of Arkansas, have performed atomistic simulations that have confirmed the existence of the new effect, which was previously predicted in theory. Their results are published in a recent issue of .

In their simulations, the researchers applied a curled electric field to nanodots made of bismuth iron oxide (BFO), which has magnetic properties. They found that, by playing with the magnitude and direction of a vector quantifying the curled electric field, they could control both the magnitude and direction of the nanodots’ magnetization.

The simulations also revealed that the effect originates from an interplay among three different components: magnetic dipoles, electric vortices, and oxygen octahedral tilts (from the BFO). When using the curled to control the nanodots’ magnetization, the researchers discovered that the process involves some peculiar intermediate states. One such state, for instance, consists of pairs of electric vortices that coexist with a single antivortex.

“Some of our findings are quite surprising and unexpected,” Ren said. “The coexistence of a vortex pair and an antivortex in ferroelectrics has never been reported before, although it is now known as an extremely interesting state in research areas.”

This understanding of the magnetotoroidic effect could enable scientists to use electric fields to better control magnetism, which could have a variety of useful applications. In their paper, the scientists mention the possibility of developing new memory devices with unprecedented storage density.

“The MT effect may find applications in the field-induced controlling of magnetic orders, switching of ferroelectric vortex, and modulation of oxygen octahedral tilts,” Ren said. “More importantly, this effect can lead the burgeoning magnetoelectric research to some new arena thanks to the rapid development of nanoscience and engineering.”

Explore further: Magnetic Vortex Switch Leads to Electric Pulse

More information: Wei Ren and L. Bellaiche. “Prediction of the Magnetotoroidic Effect from Atomistic Simulations.” Physical Review Letters 107, 127202 (2011). DOI:10.1103/PhysRevLett.107.127202


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5 / 5 (4) Sep 26, 2011
The wording on this article is extremely ambiguous and confusing. "In their simulations, the researchers applied a curled electric field..." Was this a simulation, as in computer model or other SIMULATION, or was this test/experiment actually conducted? If the former, "confirmed the existence of the new effect" is t - model and simulations can't confirm real world effects, they can only suggest or predict them. If the latter, e.g., a real world test, then the research wasn't a simulation, it was a text or experiment, which can confirm new effects. So which is it?

Furthermore, how can something that has never been reported before simultaneously be a known hot area of research?

Finally, the OI link to the actual paper fails - it returns a DOI error - so it's impossible to go directly to the paper to check these things unless one is willing to search the paper out themselves, assuming it actually exists in Phys Rev Letters.
1 / 5 (2) Sep 26, 2011
They were simulating atoms using nano dots, "researchers applied a curled electric field to nanodots made of bismuth iron oxide (BFO)." The effect was physically observed.
1 / 5 (1) Sep 26, 2011
To clarify "simulation" doesn't necessarily mean that a computer was involved, just that they were modeling a complex system with a simpler system. In this case they were modeling atom using nanodots. Simulation, in this case, does not imply that the experiment was not performed in the real world, rather that the effect was observed in a nanodot model of an atom. The effect was observed, just not in a real atom.
4 / 5 (1) Sep 27, 2011
Is the only interest in research science these days to "develope new memory devices with unprecedented storage density"?.
1 / 5 (1) Sep 27, 2011
.. by playing with ..
- from the article.

A new scientific expression? Certainly familiar to some comment contributors and now evidence that Deesky is doing at least doing something scientific with himself!
5 / 5 (1) Oct 07, 2011
Graphene, an exotic form of carbon consisting of sheets a single atom thick, exhibits a novel reaction to light, and the material can produce electric current in unusual ways. So my question is, can we use the unique properties of graphene for the purposes of producing a controlled, magnetotoroidic type effect for the purposes of magnetic based propulsion and is such research being conducted? This effect is shown to exhibit itself by applying curled electric fields on physical properties of stress-free BiFeO3 dots being under open-circuit electrical boundary conditions and since these fields can lead to a control of not only the magnitude but also the direction of the magnetization. I am curious to the possibilities of how these fields can applied as a means of propulsion. The benefits of this would be obvious and as the means to create an electric field with Graphene involve light; it would seem an area of research worth pursuing.

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