June 2009

A team of Virginia Commonwealth University scientists has discovered a ‘magnetic superatom’ – a stable cluster of atoms that can mimic different elements of the periodic table – that one day may be used to create molecular electronic devices for the next generation of faster computers with larger memory storage.

The team examined the electronic and magnetic properties of clusters having one vanadium atom surrounded by multiple cesium atoms. They found that when the cluster had eight cesium atoms it acquired extra stability due to a filled electronic state. An atom is in a stable configuration when its outermost shell is full. Consequently, when an atom combines with other atoms, it tends to lose or gain valence electrons to acquire a stable configuration.

There's a free discussion meeting in London, UK, about Spintronics. It will take place at 28-29  September 2009, at The Royal Society, London. Here's what the organizers say:

Recent advances in generating, manipulating and detecting spin-polarized electrons promise entirely new classes of spin based sensor, memory and logic devices, generally referred to as the field of spintronics.

Scientists are studying a new phenomenon called "colossal magnetoresistance effect" (CMR), which is up to a thousand times more powerful than Giant Mmagnetoresistance effect (GMR) which is used in hard-drives today.

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

Magnetic ordering in manganit sketch

“The results imply that even at ambient conditions, the manganite might already have two separate magnetic phases at the nanometer scale, with pressure favoring the growth of the antiferro-magnetic phase at the expense of the ferromagnetic phase,” said coauthor Daniel Haskel, a physicist at Argonne’s APS. “Manipulating phase separation at the nanoscale level is at the very core of nanotechnology and manganites provide an excellent playground to pursue this objective”

Ramamoorthy Ramesh, along with his colleagues at Berkeley Lab’s Materials Sciences Division in the US, successfully demonstrated that electric fields can be used as ON/OFF switches in doped multiferroic films. Multiferroics are materials in which unique combinations of electric and magnetic properties can simultaneously coexist.

They are potential cornerstones in future magnetic data storage and spintronic devices provided a simple and fast way can be found to turn their electric and magnetic properties on and off.