Discovery of material with amazing properties

Jun 24, 2012
The "8-armed candlestick" in this unusual image of the measurements is proof that the "walls" of the domains in TbFeO3 repel each other at certain temperatures and therefore lie at a fixed distance from each other. The signal from the "ordinary" chaotic domain walls would more resemble a fly swatter. Credit: Niels Bohr Institute

Normally a material can be either magnetically or electrically polarized, but not both. Now researchers at the Niels Bohr Institute at the University of Copenhagen have studied a material that is simultaneously magnetically and electrically polarizable. This opens up new possibilities, for example, for sensors in technology of the future. The results have been published in the scientific journal, Nature Materials.

Materials that can be both magnetically and electrically polarized and also have additional properties are called multiferroics and were previously discovered by Russian researchers in the 1960s. But the technology to examine the materials did not exist at that time. It is only now, in recent years, that researchers have once again focused on analyzing the properties of such materials. Now you have research facilities that can analyze the materials down to the .

Surprising test results

"We have studied the rare, naturally occurring iron compound, TbFeO3, using powerful neutron radiation in a . The temperature was cooled down to near , minus 271 C. We were able to identify that the atoms in the material are arranged in a congruent consisting of rows of the heavy metal terbium separated by iron and . Such are well known, but their are new. Normally, the magnetic domains lie a bit helter-skelter, but here we observed that they lay straight as an arrow with the same distance between them. We were completely stunned when we saw it," explains Kim Lefmann, Associate Professor at the Nano-Science Center, University of Copenhagen.

In TbFeO3 researchers discovered an unusual spin order for the magnetic field where the change in spin direction along a line of atoms occurs suddenly. There is a formation of what is known as a soliton domain wall. The size of the spin-up (or down) domains is approx. 20 nanometer, while the domain walls are a few tenths of nanometer, which is a very unusual combination. In the lower figure one of these domain walls is illustrated, whose sharpness is caused by the large amount of congruent diffraction data for the so-called candlestick figure. The upper figure shows how these domain walls can appear in more traditional materials, where the wall is thicker and the spin rotates slowly from up-mode to down-mode from left to right. Credit: Niels Bohr Institute

They were very strange and very beautiful measurements and it is just such a discovery that can awaken the researchers' intense interest. Why does it look like this?

Explaining physics

The experiments were conducted at the neutron research facility Helmholtz-Zentrum in Berlin in collaboration with researchers in Holland, Germany, at ESS in Lund and at Risø/DTU. They would like to get a general understanding of the material and with the help of calculations; and have now arrived at a more precise image of the relationship between the structure of the material and its physical properties.

"What the models are describing is that the terbium walls interact by exchanging waves of spin (magnetism), which is transferred through the magnetic iron lattice. The result is a Yukawa-like force, which is known from nuclear and particle physics. The material exhibits in a sense the same interacting forces that hold the particles together in atomic nuclei," explains Heloisa Bordallo, Associate Professor at the Niels Bohr Institute.

It is precisely this interaction between the transition metal, iron, and the rare element, terbium, that plays an important role in this magneto-electrical material. The terbium's waves of spin cause a significant increase in the electric polarization and the interaction between the ions of the elements creates one of the strongest magneto-electrical effects observed in materials.

"Through these results we found a new pathway to discover and develop new multiferroics", emphasize the researchers in the group. Now it is up to further research to determine whether this new effect could lead to new applications of these materials with the amazing physical properties.

Explore further: Technique simplifies the creation of high-tech crystals

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User comments : 10

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rah
3 / 5 (2) Jun 24, 2012
How much did the cryonic (0 degree K) temperature have to do with creating the observed properties?
Macksb
2 / 5 (4) Jun 24, 2012
Back in the late 1960s, Art Winfree developed a law of coupled oscillators. He explained that oscillators have a tendency to couple their oscillations, resulting in self-organization according to certain specific and exact patterns. The simplest such pattern is synchronous (up) and exactly antisynchronous (down). That produced the "stunning" pic.

The "normal" picture is also a Winfree pattern. In a three oscillator system, each may be one third out of phase (i.e. equal) in respect to the other two. The "normal" picture above shows that in a 180 degree transition, the oscillators space their changes at 45 degrees from their neighbor on either side. Changed temps (frequency) caused the self-organization to change. Change will be sudden, absent special constraints.

Prof. Winfree is known in the field of biomathematics. He does not seem to be well known in physics. I believe his law applies to all phases of matter--solid, liquid, gas, plasma, superconductor and other states.
Shabs42
1 / 5 (2) Jun 24, 2012
How much did the cryonic (0 degree K) temperature have to do with creating the observed properties?


My thoughts exactly. Is this just another superconductivity that will be cool in theory, but take decades to really figure out; or will this find uses more immediately?
Kedas
5 / 5 (2) Jun 25, 2012
Since it a science article:
It is degree Celsius (°C) not 'C'
And Kelvin (K) not 'degree K'
vacuum-mechanics
1.7 / 5 (6) Jun 25, 2012
By the way, talking about magnetic field it is interesting to note that nowadays conventional physics still could not understand why and how electron or atom spin create magnetic field. Armed with an unconventional way below could give some idea.
http://www.vacuum...id=21=en
TkClick
2 / 5 (4) Jun 25, 2012
This behaviour is not so exceptional. Few truly multiferroic materials exist, but the magnetoelectric coupling of magnetic and electrical properties is more widespread. A small piece of magnetoelectric material can be placed in the quantum vacuum and then rotated 180 degrees. The random magnetic fields can induce a change in electric polarization in the block of material. It has been proposed that this change causes the combined electric and magnetic fields to push the block in one direction while the fields get pushed in the other direction. The trick doesn't work if the magnetoelectric block is too large, but curiously it should work if there's a grid of many tiny blocks working together. The authors of the paper suggested that the mechanism could be used would be powerful enough to reorient satellites like with using of reactionless drive.
TkClick
2.6 / 5 (5) Jun 25, 2012
@Macksb, vacuum-mechanics: just because you're spamming with the same copy&paste posts bellow articles about both superconductivity both multiferroics, it's evident that your silly posts aren't relevant to both of superconductivity, both of multiferroics. If you have nothing particular to say about subject, don't say it here. What you believe in or not is not relevant to subject as well.
CardacianNeverid
2.5 / 5 (8) Jun 25, 2012
@Macksb, vacuum-mechanics: just because you're spamming with the same copy&paste posts bellow articles about both superconductivity both multiferroics, it's evident that your silly posts aren't relevant to both of superconductivity, both of multiferroics. If you have nothing particular to say about subject, don't say it here. What you believe in or not is not relevant to subject as well -ZephirTard

Ha, ha, ha, ha, ha! One crank getting cranky at another crank for doing exactly what he does! Priceless!
TkClick
2.6 / 5 (5) Jun 25, 2012
getting cranky at another crank for doing exactly what he does
I'm using logics in my deductions, which you apparently didn't understand. My posts aren't repetitive and when the dense aether model has nothing to say about particular article (like this one), then I simply remain quiet about it. I'm here for explanations of things in all ways possible - not for promotion of some particular theory.
El_Nose
5 / 5 (5) Jun 25, 2012
Not many people read the article --- this is not about a superconductor -- it is not about a material that is a conductor and a magnet

-- it is about a material that can be polarized both magnetically and electrically

this is unusual, please read thoroughly

the polarization can be tuned without dropping it to zero K -- but to look at the atomic structure it needs to be cold so that you can see the atoms.