Australian researchers have reviewed exciting new candidates for next-generation spintronics.

‘Spintronics’ is a new kind of electronics that exploits the spin of an electron in addition to its charge state, with the potential to increase the efficiency of data storage and transfer.

The new review covers spin-gapless semiconductors (SGSs), a new class of 'zero bandgap' materials which have fully spin-polarised electrons and holes.

It is intended to assist the search for materials that would allow for ultra-fast, ultra-low energy ‘spintronic‘ electronics with no wasted dissipation of energy from electrical conduction.

The defining property of SGS materials relates to their ‘bandgap’, the gap between the material’s valence and conduction bands, which defines their electronic properties.

In general, one spin channel (i.e, one of the spin directions, up or down) is semiconducting with a finite band gap, while the other spin channel has a closed (zero) band gap.

In a spin-gapless semiconductor (SGS), conduction and valence band edges touch in one spin channel, and no threshold energy is required to move electrons from occupied (valence) states to empty (conduction) states.

This property gives these materials unique properties: their band structures are extremely sensitive to external influences (like pressure or magnetic field).

The review paper Spin-Gapless Semiconductors is accessible here.