Saturday, May 7, 2011
Graphene is produced from graphite - looks to have quite a future as does Focus Metals
A team led by Professor Andre Geim, a recipient of the 2010 Nobel Prize for graphene, can now show that electric current – a flow of electrons – can magnetise graphene.
The results, reported in Science, could be a potentially huge breakthrough in the field of spintronics.
Spintronics is a group of emerging technologies that exploit the intrinsic spin of the electron, in addition to its fundamental electric charge that is exploited in microelectronics.
Billions of spintronics devices such as sensors and memories are already being produced. Every hard disk drive has a magnetic sensor that uses a flow of spins, and magnetic random access memory (MRAM) chips are becoming increasingly popular.
The findings are part of a large international effort involving research groups from the US, Russia, Japan and the Netherlands.
The key feature for spintronics is to connect the electron spin to electric current as current can be manipulated by means routinely used in microelectronics.
It is believed that, in future spintronics devices and transistors, coupling between the current and spin will be direct, without using magnetic materials to inject spins as it is done at the moment.
So far, this route has only been demonstrated by using materials with so-called spin-orbit interaction, in which tiny magnetic fields created by nuclei affect the motion of electrons through a crystal. The effect is generally small which makes it difficult to use.
The researchers found a new way to interconnect spin and charge by applying a relatively weak magnetic field to graphene and found that this causes a flow of spins in the direction perpendicular to electric current, making a graphene sheet magnetised.
The effect resembles the one caused by spin-orbit interaction but is larger and can be tuned by varying the external magnetic field.
The Manchester researchers also show that graphene placed on boron nitride is an ideal material for spintronics because the induced magnetism extends over macroscopic distances from the current path without decay.
The team believes their discovery offers numerous opportunities for redesigning current spintronics devices and making new ones such as spin-based transistors.
Professor Geim said: “The holy grail of spintronics is the conversion of electricity into magnetism or vice versa.
“We offer a new mechanism, thanks to unique properties of graphene. I imagine that many venues of spintronics can benefit from this finding.”
Antonio Castro Neto, a physics professor from Boston who wrote a news article for the Science magazine which accompanies the research paper commented: “Graphene is opening doors for many new technologies.
“Not surprisingly, the 2010 Nobel Physics prize was awarded to Andre Geim and Kostya Novoselov for their groundbreaking experiments in this material.
“Apparently not satisfied with what they have accomplished so far, Geim and his collaborators have now demonstrated another completely unexpected effect that involves quantum mechanics at ambient conditions. This discovery opens a new chapter to the short but rich history of graphene”.
To add to the above report on studies currently being done on graphene comes this informative piece.
UMD Scientists Make Magnetic New Graphene Discovery
COLLEGE PARK, Md. -- University of Maryland researchers have discovered a way to control magnetic properties of graphene that could lead to powerful new applications in magnetic storage and magnetic random access memory.
The finding by a team of Maryland researchers, led by Physics Professor Michael S. Fuhrer of the UMD Center for Nanophysics and Advanced Materials is the latest of many amazing properties discovered for graphene.
A honeycomb sheet of carbon atoms just one atom thick, graphene is the basic constituent of graphite. Some 200 times stronger than steel, it conducts electricity at room temperature better than any other known material (a 2008 discovery by Fuhrer, et. al). Graphene is widely seen as having great, perhaps even revolutionary, potential for nanotechnology applications. The 2010 Nobel Prize in physics was awarded to scientists Konstantin Novoselov and Andre Geim for their 2004 discovery of how to make graphene.
In their new graphene discovery, Fuhrer and his University of Maryland colleagues have found that missing atoms in graphene, called vacancies, act as tiny magnets -- they have a "magnetic moment." Moreover, these magnetic moments interact strongly with the electrons in graphene which carry electrical currents, giving rise to a significant extra electrical resistance at low temperature, known as the Kondo effect. The results appear in the paper "Tunable Kondo effect in graphene with defects" published this month in Nature Physics.
The Kondo effect is typically associated with adding tiny amounts of magnetic metal atoms, such as iron or nickel, to a non-magnetic metal, such as gold or copper. Finding the Kondo effect in graphene with vacancies was surprising for two reasons, according to Fuhrer.
"First, we were studying a system of nothing but carbon, without adding any traditionally magnetic impurities. Second, graphene has a very small electron density, which would be expected to make the Kondo effect appear only at extremely low temperatures," he said.
The team measured the characteristic temperature for the Kondo effect in graphene with vacancies to be as high as 90 Kelvin, which is comparable to that seen in metals with very high electron densities. Moreover the Kondo temperature can be tuned by the voltage on an electrical gate, an effect not seen in metals. They theorize that the same unusual properties of that result in graphene'sKondo effect at a relatively high temperature.
Fuhrer thinks that if vacancies in graphene could be arranged in just the right way, ferromagnetism could result. "Individual magnetic moments can be coupled together through the Kondo effect, forcing them all to line up in the same direction," he said.
"The result would be a ferromagnet, like iron, but instead made only of carbon. Magnetism in graphene could lead to new types of nanoscale sensors of magnetic fields. And, when coupled with graphene's tremendous electrical properties, magnetism in graphene could also have interesting applications in the area of spintronics, which uses the magnetic moment of the electron, instead of its electric charge, to represent the information in a computer.
"This opens the possibility of 'defect engineering' in graphene - plucking out atoms in the right places to design the magnetic properties you want," said Fuhrer.
This research was supported by grants from the National Science Foundation and the Office of Naval Research.
Graphite is commonly known to exist on the critical mineral list of the US as well as EU, and I would expect many other countries as well. The fact that graphite is not really that rare, is overshadowed by the fact that, most known graphite deposits in the world vary from a carbon content of 2% to 5%. This makes finding highly economically viable deposits the rarity. Focus Metals (TSXV:FMS) has a marked advantage over most, if not all competitors, in that their Lac Knife deposit grades 17% carbon content. Add to that the fact that Lac Knife holds approximately 8.1 million tonnes of graphite, which is open in several directions for possible further expansion of additional resources, and also contains a very high percentage of large flake graphite. This all speaks volumes as to just what type of world class deposit this really is shaping up to be. China as we know controls between 75% - 80% of the graphite production globally at present and they have graphite on their list of restricted export list. This will help to continually drive the price of graphite, along with the major increase we are starting to see build momentum from numerous buyers, should leave Focus Metals poised to take advantage of not only the sales of graphite but also purified graphite that will then be used in much more technical settings and which bring distinctively higher prices.
The management of Focus Metals seems to be at the very top of their game currently as this company begins to take on a much more sophisticated and fuller shape. It is quite compelling as we watch every step and decision they have made thus far and how all of this is progressing this company towards their end goal of becoming a world class mine to market company.
For disclosure purposes I have received no compensation of any kind for this post. I own shares in FMS.
Posted by brujacman at 5/07/2011 11:56:00 AM