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August 14, 2009

Magnetic Silicon Fullerene and London Nanospintronic Projects

1. Magnetic Silicon Fullerene

A magnetic metal-encapsulating silicon fullerene, Eu@Si20, has been predicted by density functional theory to be by far the most stable fullerene-like silicon structure. The Eu@Si20 structure is a regular dodecahedron with Ih symmetry in which the europium atom occupies the center site. The calculated results show that the europium 10 atom has a large magnetic moment of nearly 7.0 Bohr magnetons. The magnetic silicon fullerene may be ideal for molecular electronic devices. In addition, it was found that two kinds of stable “pearl necklace” nanowires, constructed by concatenating a series of Ih-Eu@Si20 units, each with a central europium atom retains the high spin moment. The magnetic structure of these nanowires indicates potential applications in the fields of spintronics and high-density magnetic storage.

2. The London Centre for Nanotechnology – a joint venture between UCL and Imperial College London – is taking a strategic lead in the emerging field of nanospintronics, by initiating collaborative projects with research groups at China’s top two universities, Peking University and Tsinghua University. The projects aim to develop radically new approaches to miniaturization of computer systems, based on the exploitation of special magnetic “spin” properties of individual molecules and single atoms.



The two projects focus on ‘silicon-based spintronics’ and ‘molecular nanospintronics’

Research highlights of the London Centre for Nanotechnology

the intriguing properties of one-dimensional (1D) systems such as magnetic ladders – literally a magnetic analogue of a step ladder – in which the magnetic moments carried by individual atoms are coupled together through rungs and legs. In 1D, long-range magnetic order is destroyed by quantum fluctuations, and theory predicts that instead a particular kind of exotic magnetic quantum liquid forms, known as a Luttinger liquid (LL). When a magnetic field is applied, this fascinating state of quantum matter becomes a key component of the extraordinary rich phase diagram of the ladder and can be studied using extremely sensitive magnetometers in the laboratory and high-resolution neutron spectroscopy. In the presence of weak magnetic links between ladders, the system can even display Bose-Einstein condensation, which underpins the remarkable properties of superfluids and superconductors

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