Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fractals add new dimension to study of tiny electronics

03.12.2002


When it comes to miniature electronics, scientists have seen the shape of things to come -- and that shape is a fractal.

People most often see fractals in the familiar, irregular branching shapes of nature -- a leaf, or tree, or snowflake. A repeating pattern of ever-smaller branches gives these structures a unique profile that defies classical geometry.

Now a study suggests that magnetic fields can take the form of fractals, too -- if a magnet is made of plastic molecules that are stacked in parallel chains.



While the results could influence the design of electronic devices in the distant future, the work is so new that scientists are only beginning to consider its implications, said Arthur Epstein, Distinguished University Professor of chemistry and physics and director of the Center for Materials Research at Ohio State University.

Epstein and longtime collaborator Joel Miller, professor of chemistry at the University of Utah, described the study in a recent issue of the journal Physical Review Letters. Coauthors included graduate students Stephen Etzkorn at Ohio State and Wendy Hibbs at the University of Utah.

Using a computer model, the scientists tried to look ahead to a time when electronic structures can be built so small that they no longer behave like normal three-dimensional objects.

“The materials currently used in magnetic devices -- for example, computer hard discs or ID strips on credit cards -- behave like three-dimensional magnets,” explained Epstein. “However, the decreasing size of these devices may one day require them to be considered one- or two-dimensional in nature. As the spatial dimensions decrease, the magnetic dimensions of the materials may take on fractal values.”

Mathematically, fractals are considered to exist in partial, or fractional, dimensions. That means if a device produced a magnetic field that exhibits fractal behavior, the magnetic field wouldn’t possess dimension equal to a whole number -- such as one, two, or three dimensions -- but rather a fractional value such as 0.8 or 1.6 dimensions.

Such a seemingly bizarre existence in fractional dimensions sounds like the stuff of science fiction, but that’s what Epstein and his colleagues found when they modeled the behavior of a plastic magnet.

The model consisted of a hybrid material, a compound of manganese tetrapheynlporphyrin and tetracyanoethylene. Theoretically, this compound can form polymer chains that are one-dimensional.

The researchers modeled the behavior of the material as it was magnetized by an external magnetic field and then cooled to a critical temperature where it began to behave as a special kind of glass. At -267ºC (-449ºF), the magnetic field of the material appeared to exist in 0.8 dimensions. As it cooled a little further, it gradually became one-dimensional, then finally settled at 1.6 dimensions at -269ºC (-452ºF).

The “spin” of the molecules -- a quality that relates to the source of magnetism and magnetic fields in materials -- appeared to form clusters within the material, with each cluster pointing its magnetic field in a different direction. Many magnetic fields sprouted out from the material like branches of a cactus. Tiny secondary magnetic fields then sprang out from the branches like needles on a cactus.

Eventually, the cacti-like branches were locked together, with crisscrossing needles holding them in place. This interlocking fractal growth gave the magnetic field a unique kind of order, and as a result, the material would be called a “fractal cluster glass,” Epstein said.

To explain this behavior, Epstein likened the one-dimensional polymer chains of this exotic compound to stacks of poker chips. “Imagine each poker chip is an atom,” he said, “and that many stacks of chips are immersed in chicken fat.”

“When the fat insulation is thin, the stacks of poker chips can all ‘see’ each other. When it comes to orienting their magnetic fields, each stack can look to its neighbor to see what it should be doing, and all the stacks can orient the same way,” he said.

“But when the chicken fat insulation is thick (as for the materials used in this study), it becomes opaque, and suddenly the stacks of poker chips can’t see each other,” he continued. “Without knowing what its neighbors are doing, each stack has to pick a random direction for its magnetic field.”

Spins of different groups of atoms within the stack may pick different directions at first. Normally, these clusters would interact with each other in a kind of competition, until the magnetic fields were all pointing in the same direction.

“Sometimes the atoms don’t have enough energy to fight with each other. Then the clusters just continue to point in random directions, and the material is considered a cluster glass,” Epstein said.

Epstein believes that cluster glasses could play a role in future electronics, when organic-based magnets could be structurally tuned to provide magnets of differing dimension.

Until then, scientists will have to probe this fractal behavior further.

“We’re just now beginning to understand these exciting phenomena,” Epstein said.

The Department of Energy and the National Science Foundation supported this work.


Arthur J. Epstein, (614) 292-1133; Epstein.2@osu.edu

Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Arthur J. Epstein | EurekAlert!
Further information:
http://www.energy.gov/
http://www.nsf.gov/
http://www.osu.edu/researchnews/archive/magfrac.htm

More articles from Physics and Astronomy:

nachricht The taming of the light screw
22.03.2019 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Magnetic micro-boats
21.03.2019 | Max-Planck-Institut für Polymerforschung

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>