Scientists explore magnetic properties of semiconductors

SOME SPECIALLY BUILT semiconductors have been found to display important magnetic properties which could lead to the development of smaller, faster gadgets.

Boffins from the National Institute of Standards and Technology (NIST), Korea University and the University Of Notre Dame carried out tests which demonstrated the rare magnetic property, prompting hopes for future magnetic data storage in semiconductor material. This potentially means faster data processing through built-in logic circuits controlled by electric fields because Semiconductors with magnetic properties would not only be able to process data, but also store it.

Magnetic data storage isn’t something new. It is currently used in computer hard drives and most MP3 players, although the actual storage device is based on metallic rather than semiconductor materials, which slows performance.

What researchers have now discovered is that, in certain circumstances, thin magnetic layers of the semiconductor material gallium arsenide (GaAs) show antiferromagnetic coupling – where a layer aligns its magnetic pole in the opposite direction to the next magnetic layer.

The research team beamed neutrons onto multilayer stacks of GaAs using a technique called ‘polarised neutron reflectometry’. Because neutrons are magnetic and can easily beam through the whole stack, any reflected neutrons demonstrated magnetic properties of individual layers clearly.

Scientists found that at very cold temperatures and small magnetic fields, the polarised neutron data clearly showed signs of antiparallel magnetic alignment in neighbouring layers occurring. Increasing the magnetic field demonstrated a parallel alignment of all layers.

The research is still some way off from finding ways to re-create the results at room-temperature, but the NIST team hopes its breakthrough will be a first definitive step in the right direction. µ

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