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Graphite mimics iron's magnetism
October 05, 2009Researchers of Eindhoven University of Technology and the Radboud University Nijmegen in The Netherlands show for the first time why ordinary graphite is a permanent magnet at room temperature. The results are promising for new applications in nanotechnology, such as sensors and detectors. In particular graphite could be a promising candidate for a biosensor material. The results will appear online on 4 October in Nature Physics.
Graphite is a well-known lubricant and forms the basis for pencils. It is a layered compound with a weak interlayer interaction between the individual carbon (graphene) sheets. Hence, this makes graphite a good lubricant.
Unexpected
It is unexpected that graphite is ferromagnetic. The researchers Jiri Cervenka and Kees Flipse (Eindhoven University of Technology) and Mikhail Katsnelson (Radboud University Nijmegen) demonstrated direct evidence for ferromagnetic order and explain the underlying mechanism. In graphite well ordered areas of carbon atoms are separated by 2 nanometer wide boundaries of defects. The electrons in the defect regions (the red/yellow area in picture 1) behave differently compared to the ordered areas (blue in picture 1), showing similarities with the electron behaviour of ferromagnetic materials like iron and cobalt.
Debate settled
The researchers found that the grain boundary regions in the individual carbon sheets are magnetically coupled, forming 2-dimensional networks (picture 2). This interlayer coupling was found to explain the permanent magnetic behaviour of graphite. The researchers also show experimental evidence for excluding magnetic impurities to be the origin of ferromagnetism, ending ten years of debate.
Carbon in spintronics
Surprisingly, a material containing only carbon atoms can be a weak ferro magnet. This opens new routes for spintronics in carbon-based materials. Spins can travel over relative long distances without spin-flip scattering and they can be flipped by small magnetic fields. Both are important for applications in spintronics. Carbon is biocompatible and the explored magnetic behaviour is therefore particularly promising for the development of biosensors.
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Publication Nature Physics
The paper in Nature Physics " Room-temperature ferromagnetism in graphite driven by 2D networks of point defects" by Jiri Cervenka, Mikhail Katsnelson and Kees Flipse will appear online Sunday 4 October, 7:00 pm CET. The paper can be found under DOI 10.1038/NPHYS1399.
The research was funded by Nanoned and FOM.
Eindhoven University of Technology
It is unexpected that graphite is ferromagnetic. The researchers Jiri Cervenka and Kees Flipse (Eindhoven University of Technology) and Mikhail Katsnelson (Radboud University Nijmegen) demonstrated direct evidence for ferromagnetic order and explain the underlying mechanism. In graphite well ordered areas of carbon atoms are separated by 2 nanometer wide boundaries of defects. The electrons in the defect regions (the red/yellow area in picture 1) behave differently compared to the ordered areas (blue in picture 1), showing similarities with the electron behaviour of ferromagnetic materials like iron and cobalt.
Debate settled
The researchers found that the grain boundary regions in the individual carbon sheets are magnetically coupled, forming 2-dimensional networks (picture 2). This interlayer coupling was found to explain the permanent magnetic behaviour of graphite. The researchers also show experimental evidence for excluding magnetic impurities to be the origin of ferromagnetism, ending ten years of debate.
Carbon in spintronics
Surprisingly, a material containing only carbon atoms can be a weak ferro magnet. This opens new routes for spintronics in carbon-based materials. Spins can travel over relative long distances without spin-flip scattering and they can be flipped by small magnetic fields. Both are important for applications in spintronics. Carbon is biocompatible and the explored magnetic behaviour is therefore particularly promising for the development of biosensors.
###
Publication Nature Physics
The paper in Nature Physics " Room-temperature ferromagnetism in graphite driven by 2D networks of point defects" by Jiri Cervenka, Mikhail Katsnelson and Kees Flipse will appear online Sunday 4 October, 7:00 pm CET. The paper can be found under DOI 10.1038/NPHYS1399.
The research was funded by Nanoned and FOM.
Eindhoven University of Technology
Ferromagnetic Current Events and Ferromagnetic News RSSPhysicists observe magnetism in gas for the first time
An international team of physicists has for the first time observed magnetic behaviour in an atomic gas, addressing a decades-old debate as to whether it is possible for a gas or liquid to become ferromagnetic and exhibit magnetic properties.
Researchers design new graphene-based, nano-material with magnetic properties
An international team of researchers has designed a new graphite-based, magnetic nano-material that acts as a semiconductor and could help material scientists create the next generation of electronic devices like microchips.
Unexpectedly long-range effects in advanced magnetic devices
A tiny grid pattern has led materials scientists at the National Institute of Standards and Technology (NIST) and the Institute of Solid State Physics in Russia to an unexpected finding-the surprisingly strong and long-range effects of certain electromagnetic nanostructures used in data storage.
Nanophysicists find unexpected magnetic effect
Spanish and U.S. physicists studying nanoelectronics have found that size really does matter when it comes to predicting the behavior of electrical contacts that are just one atom wide.
Argonne scientists pinpoint mechanism to increase magnetic response of ferromagnetic semiconductor
When squeezed, electrons increase their ability to move around. In compounds such as semiconductors and electrical insulators, such squeezing can dramatically change the electrical- and magnetic- properties.
NRL partners with industry to develop compact biosensor for wide-ranging applications
Scientists at the Naval Research Laboratory (NRL) are partnering with industry to develop a sensor system for biomolecules that could make a significant contribution to a variety of fields such as healthcare, veterinary diagnostics, food safety, environmental testing, and national security.
Investigation of changes in properties of water under the action of a magnetic field
Professor Pang Xiao-Feng and Deng Bo studied the properties of water, and their changes under the action of a magnetic field were gathered by the spectrum techniques of infrared, Raman, visible, ultraviolet and X-ray lights, which may give an insight into molecular and atomic structures of water.
Powerful superconductor is in a class all its own
Superconductivity has perplexed, astounded and inspired scientists ever since it was discovered in 1911. Now, in the latest of a century of surprises, researchers at the National High Magnetic Field Laboratory at Florida State University have discovered unusual properties in a novel superconducting material that point to an entirely new kind of superconductor.
NRL generates, modulates, and electrically detects pure spin currents in silicon
Scientists at the Naval Research Laboratory (NRL) have generated, modulated and electrically detected a pure spin current in silicon, the semiconductor used most widely in the electronic device industry.
Measurements from the edge: magnetic properties of thin films
Materials researchers at the National Institute of Standards and Technology (NIST), together with colleagues from IBM and the Massachusetts Institute of Technology, have pushed the measurement of thin films to the edge-literally-to produce the first data on how the edges of metallic thin films contribute to their magnetic properties.
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