Evidence of magnetic superatoms could open doors to new spin electronics

March 22, 2013 by Lisa Zyga feature
As part of their investigation of magnetic superatoms, the researchers investigated the ground states of clusters made of sodium and vanadium atoms (brown and yellow circles, respectively). Credit: Xinxing Zhang, et al. ©2013 American Chemical Society

(Phys.org) —Scientists have found evidence for the existence of magnetic superatoms—small, compact clusters of atoms whose electrons occupy a set of orbitals around the entire cluster rather than around the individual atoms. If scientists can synthesize superatoms with magnetic properties, then one day they may use them to create new spin-dependent electronics.

The researchers, Xinxing Zhang, et al., from Johns Hopkins University in Baltimore, Maryland; Universitaet Konstanz in Konstanz, Germany; and Virginia Commonwealth University in Richmond, Virginia, have published their findings on magnetic superatoms in a recent issue of the Journal of the American Chemical Society.

To find evidence for the existence of stable, magnetic superatoms, the researchers probed the superatoms' orbitals, ground states, spin properties, and using first principles calculations and spectroscopy experiments.

Previous research has shown that, while the orbital shapes of superatoms resemble those of single atoms, electrons fill orbitals in superatoms differently than they fill those in single atoms. In single atoms, orbital filling follows Hund's rule, so that every orbital in a subshell is occupied with one electron before any orbital is doubly occupied. This approach generally leads to greater atomic stability.

However, superatom orbitals are filled differently due to spatial distortions, with the result being that superatoms are generally non-magnetic. One way to stabilize magnetic superatoms is to introduce an additional transition that can breed magnetism through its specific orbital configuration that hybridizes with the superatom and stabilizes the magnetic state.

In the new study, the scientists showed that a non-magnetic cluster consisting of eight can be made magnetic by adding a vanadium atom to fill certain orbitals. The result is a stable magnetic superatom VNa8 that can be synthesized inside molecular beams.

"While making VNa8 species in molecular beams was not difficult, one should expect that making them in macroscopic quantities would be more challenging," coauthor Kit Bowen, a professor of chemical physics at Johns Hopkins University, told Phys.org.

The magnetic superatoms could be of interest for practical purposes if they can be supported on a substrate and used to generate spin-polarized electric currents. In this way, the magnetic superatoms could be used to build spin-dependent electronics.

"The new superatoms will have great potential in molecular electronic devices for spintronics and other applications," said coauthor Shiv Khanna, a physics professor at Virginia Commonwealth University. "In a recent work, my group has shown that a molecule made of two superatoms can lead to highly spin polarized currents. The minimal spin orbit would ensure that the electron spin maintains its direction for a longer time, which is important for applications in spintronics. We have also found that such devices can lead to high magneto resistance."

The researchers have future plans to continue exploring magnetic superatoms and what can be done with them.

"My group is now engaged in furthering our concept to propose different classes of such superatoms and the properties offered by each group," Khanna said. "On the other hand, we are talking with synthetic chemists to explore if we can make a material consisting of an assembly of magnetic superatomic building blocks."

Explore further: Scientists discover magnetic superatoms

More information: Xinxing Zhang, et al. "On the Existence of Designer Magnetic Superatoms." Journal of the American Chemical Society. DOI: 10.1021/ja400830z

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4 comments

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El_Nose
2.8 / 5 (6) Mar 22, 2013
next up superatom roomtemp superconductors for the win

but this really should be expected ... and beofre you think I am one of those annoying know it alls with no Ph.d comment unproven belief's .. cause I assure you I am ;-)

http://phys.org/n...tml#nRlv

is an article on superatoms with the chemical makeup of VCs8
where they found that adding Vandium to the superatom Cs8 make it a stable magnetic superatom ... and since Cs and Na are in the alkali metals category -- i'm going out on a limb and annoucing to the world that VRb8 VK8 and VLi8 are all going to have this wonderful property... darned if I know how to synthesize them though.
El_Nose
2.6 / 5 (7) Mar 22, 2013
I leave the synthesis to those getting paid to work in this field ... no need to thank me for your next grant proposal, I will humbly accept name recognition in the next three or four published papers that you choose to write. When you accept the Nobel, a simple nod in my direction is all the recognition i desire. I freely share this idea with the world. But if you should run across a few swedish girls with questionable morals and daddy issues then give me a call and we can forgive the name recognition
Laurence Cooper
5 / 5 (1) Mar 22, 2013
This is very interesting for a number of reasons, I think I am going to sit down and think of a few applications for their use.
arq
not rated yet Mar 23, 2013
Evidence of what?? when they have been discovered more than three years back!

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