"Colossal" Magnetoresistance to further revolutionise storage

Giant Magnetoresistance (GMR) revolutionised storage since its discovery some 20 years ago, winning the Nobel prize and allowing devices like the iPod to store massive amounts of data in tiny spaces. June 12th edition of Phys Rev Letters published a paper by Yang Ding and team of the Carnegie Institution’s High Pressure Synergetic Center (HPSync) describing a new approach yielding an effect 1000 times more powerful than GMR, dubbed Colossal Magnetoresistance (CMR).

The researchers found that when manganite was subjected to 230,000 times atmospheric pressure it underwent a transition from a ferromagnetic type (electron spins aligned) to an antiferromagnetic type (electron spins opposed). This transition was accompanied by a non-uniform structural Jahn-Teller effect distortion.

There's a long way to go before simple applications of the approach, but what were considered fundamental magnetic reading limits using magnetoresistance effects are again evaporating.

See Carnegie Institution for Science.

Holographic storage puts 100 DVDs on a single disc

General Electric says it has achieved a breakthrough in digital storage technology that will allow standard-size discs to hold the equivalent of 100 DVDs. The storage technique, which G.E. is detailing next Monday, is just a laboratory success at this stage. The new technology must be made to work in products that can be mass-produced at affordable prices. The holographic process consists of data encoded in light patterns that are stored in light-sensitive material.

Holographic storage has the potential to pack data far more densely than conventional optical technology, used in DVDs and the newer, high-capacity Blu-ray discs, in which information is stored as a pattern of marks across the surface of a disc. The potential of holographic technology has long been known. The first research papers were published in the early 1960s.

See New York Times.

New kind of superconductor immune to magnetic fields?

It appears that National High Magnetic Field Laboratory scientists at Florida State University have discovered some unexpected properties in a novel superconducting material that indicate an entirely new class of superconductor.

It's long been known that the superconducting state, which is a quantum collective state of the conductors in a material, expels magnetic fields from a solid. But at sufficiently high fields, the field will penetrate and destroy the superconducting state. But the superconducting state in the recently formulated iron oxyarsenide superconductor has remained stable in a magnetic field all the way up to a whopping 45 Tesla, far past the critical field points at which all known superconductors become normal conductors.

This is significant for future technology. To quote the article: "A high tolerance for magnetic field is one of three key properties researchers hope for in superconductors. Also desirable are the abilities to operate at relatively high temperatures and in the presence of high electrical currents. Superconductors are used to make MRI and research magnets, and now they are being tested in a new generation of superconducting electric motors, generators, transformers and power transmission lines. Today, the most powerful superconducting magnet generates a field of about 26 Tesla. If a superconductor could be found that tolerates a higher current and field, it may make possible more powerful magnets, opening up vast new research areas to scientists and power applications."

See Eurekalert.

New Quantum State of Matter?

In a Nature article published yesterday, Princeton University scientists have shown that the Quantum Hall Effect can occur in nature in a way that wasn't predicted - they've recorded the behavior of electrons in a bulk crystal of bismuth-antimony without any external magnetic field being present. The fundamental research could also lead to advances in new kinds of fast quantum or "spintronic" computing devices.

The Quantum Hall Effect has only been seen previously in atomically thin layers of semiconductors in the presence of a very high applied magnetic field.

See Science Daily.

Graphene may replace silicon in large scale integration

University of Maryland physicists have shown that in graphene the intrinsic limit to the mobility, a measure of how well a material conducts electricity, is higher than any other known material at room temperature.

See U Maryland.

Production targeting 10m2 carbon nanotube sheets

Nanocomp Technologies of Concord, USA says it can now produce sheets of carbon nanotubes that measure 1m by 2m and will reach 10 square metres in area by this summer. The sheets, which the company can produce on its single machine at a rate of one per day, are composed of a series of nanotubes each about a millimeter long, overlapping each other randomly to form a thin mat. The tensile strength of the mat ranges from 200 to 500 megapascals. A sheet of aluminum of equivalent thickness, for comparison, has a strength of 500 megapascals.

See xconomy.com.

Self healing polymer rebonds after cutting

A new material can rebond itself when cut and retain elasticity. Rubbersied materials gets their elasticity from long chains of polymer molecules that are crosslinked in three different ways: through covalent, ionic, and hydrogen bonding between molecules. Of these three bond types, only the hydrogen bonds can be remade once a material is fractured, although normally there are not enough hydrogen bonds available to re-couple in this way. Rebonding can be achieved after breaking or cutting by devising a material that gets rid of the ionic and covalent bonds in faour of hydrogenic only.

See New Scientist.
and on YouTube: video of cutting and mending

3D nanostructures grown using DNA templating

Researchers at the U.S. Department of Energy's Brookhaven National Laboratory have used DNA to guide the creation of three-dimensional, ordered, crystalline structures of nanoparticles. The ability to engineer such 3-D structures is essential to producing functional materials that take advantage of the unique properties that may exist at the nanoscale.

See Science Daily.

Nanowires lead revolutionary change in battery technology

Stanford researchers have used silicon nanowires to revolutionise rechargeable lithium-ion battery technology. Research led by Yi Cui, assistant professor of materials science and engineering, has led to technology that produces 10 times the amount of electricity of existing lithium-ion, known as Li-ion, batteries. A laptop that now runs on battery for two hours could operate for 20 hours.

"It's not a small improvement," Cui said. "It's a revolutionary development."

See Stanford News.

New carbon nanotube fibre outperforms Kevlar

A new type of continuous carbon fibre, developed a group at the Department of Materials Science and Metallurgy at Cambridge, could be woven into super-strong fabric, with potential uses for body armour for the military and law enforcement.

Made from carbon nanotubes, the researchers say their material is already several times stronger, tougher and stiffer than Kevlar fibres currently used to make protective armour.


See BBC News.