Big success with tiny crystals
Magnetism - large and small
A little piece of iron wire is magnetic – just like a huge iron rod. When it comes to material properties, size usually does not matter. Surprisingly, researchers from Austria and India have now discovered that some materials show very unusual behavior, when they are studied in the form of tiny crystals. This could now lead to new materials with tailor-made electronic and magnetic properties.
Material properties such as electrical conductivity, magnetic properties or the melting point do not depend on an object’s size and shape. “In India, however, an experiment recently showed that special manganese oxides – so called manganites – exhibit completely different properties, when their size is reduced to tiny grains”, Karsten Held explains.
A team of scientists from the Vienna University of Technology (Austria) and the S.N. Bose National Centre Kolkata (India) investigated this phenomenon – and the new effect could be explained in computer simulations. In a crossover from large crystals to smaller crystals, the distribution of the electrons changes, and so does their energy. This, in turn, changes the electrical and magnetic properties of the crystal. “The phenomenon of quantum entanglement plays a very important role here”, says Professor Karsten Held. “We cannot think of the electrons as classical particles, moving independently of each other, on well-separated paths. The electrons can only be described collectively.”
By changing their size, the properties of the manganite-crystals can now be harnessed. Larger crystals are insulators, and they are not magnetic. Tiny crystal pieces on the other hand turn out to be metallic ferromagnets.
Phase transitions, at which important material properties change, play a major role in technological applications: “When data is read from a hard-drive with a reading head, a transition between a conducting and a non-conducting state is used”, Karsten Held explains. Similar effects can be seen in manganite crystals: “We knew that magnetic properties of manganites depend on the temperature and the magnetic field”, says Tanusri Saha-Dasgupta, a material scientist at the S.N. Bose National Centre Kolkata . “But now we know that these transitions can also be controlled by altering the size of the crystals.” By changing the granular size of the crystals, the scientists can influence the critical temperature and magnetic field strength, at which the phase transition takes place. For technological applications, this opens up exciting new possibilities.
The manganite crystals studied by the Austro-Indian research team are only some three to fifteen billionths of a meter wide – but still they consist of hundreds or thousands of atoms. Simulating their behavior on a computer is therefore still a great challenge. “The quantum mechanical equations we are dealing with here can only be solved with extremely powerful computer clusters”, says PhD-student Angelo Valli. “Fortunately, the computer cluster VSC at the Vienna University of Technology provides us with remarkable computing power.”
More information: http://prl.aps.org … /i19/e197202
Provided by Vienna University of Technology
-
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor,
32 comments
-
Thioridazine kills cancer stem cells in human while avoiding toxic side-effects of conventional cancer treatments,
3 comments
-
SpaceX private rocket blasts off for space station (Update),
42 comments
-
Climate scientists say they have solved riddle of rising sea,
31 comments
-
SpaceX capsule has 'new car' smell, astronauts say (Update),
4 comments
-
Laser noise spectrum
2 hours ago
-
Transparency of molten substances?
May 25, 2012
-
saturated paramagnetic and ferromagnetic
May 24, 2012
-
How to calculate the bandstructure of Twisted Bilayer Graphene
May 23, 2012
-
vast computational richness from swapping one proton
May 22, 2012
-
Oscillator strength of mixed LH- and HH-excitons
May 22, 2012
- More from Physics Forums - Atomic, Solid State, Comp. Physics
More news stories
Is a classical electrodynamics law incompatible with special relativity?
(Phys.org) -- The laws of classical electromagnetism that were developed in the 19th century are the same laws that scientists use today. They include Maxwell’s four equations along with the Lorentz la ...
May 24, 2012 |
4.7 / 5 (17) |
43
|
Landmark calculation clears the way to answering how matter is formed
(Phys.org) -- An international collaboration of scientists, including Thomas Blum, associate professor of physics, is reporting in landmark detail the decay process of a subatomic particle called a kaon – ...
May 25, 2012 |
4.3 / 5 (22) |
51
|
Lying in wait for WIMPs: Researchers seek to dramatically increase sensitivity of Large Underground Xenon detector
Although it's invisible, dark matter accounts for at least 80 percent of the matter in the universe. No one knows what it is, but most scientists would bet on weakly interacting massive particles, or WIMPs.
May 23, 2012 |
4 / 5 (7) |
16
|
Hawaii lab turns laser-powered bubbles into microrobots
(Phys.org) -- A team of scientists from the University of Hawaii are working on microrobots created from bubbles of air in a saline solution. The bubbles take on their title of “robots” as a laser ...
May 23, 2012 |
5 / 5 (4) |
2
|
Sound increases the efficiency of boiling
Scientists at the Georgia Institute of Technology achieved a 17-percent increase in boiling efficiency by using an acoustic field to enhance heat transfer. The acoustic field does this by efficiently removing vapor bubbles ...
May 24, 2012 |
5 / 5 (2) |
2
Land and sea species differ in climate change response: study
(Phys.org) -- Marine and terrestrial species will likely differ in their responses to climate warming, new research by Simon Fraser University and Australia’s University of Tasmania has found.
Almost half of new vets seek disability
(AP) -- America's newest veterans are filing for disability benefits at a historic rate, claiming to be the most medically and mentally troubled generation of former troops the nation has ever seen.
'Unzipped' carbon nanotubes could help energize fuel cells, batteries
Multi-walled carbon nanotubes riddled with defects and impurities on the outside could replace some of the expensive platinum catalysts used in fuel cells and metal-air batteries, according to scientists at ...
T cells 'hunt' parasites like animal predators seek prey, study shows
By pairing an intimate knowledge of immune-system function with a deep understanding of statistical physics, a cross-disciplinary team at the University of Pennsylvania has arrived at a surprising finding: T cells use a movement ...
Computer model used to pinpoint prime materials for efficient carbon capture
When power plants begin capturing their carbon emissions to reduce greenhouse gases – and to most in the electric power industry, it's a question of when, not if – it will be an expensive undertaking.
Change in developmental timing was crucial in the evolutionary shift from dinosaurs to birds: study
At first glance, it's hard to see how a common house sparrow and a Tyrannosaurus Rex might have anything in common. After all, one is a bird that weighs less than an ounce, and the other is a dinosaur that ...
