Component incorporates spin and molecular electronics

Scientists have created an electronic component based on a single organic molecule using the techniques of both spin and molecular electronics.

At just one nanometre in diameter, the current device represents something of a breakthrough and compares with carbon nanotube-based transistors that are on the scale of tens of nanometres.

In the current project, the researchers demonstrated that the organic molecule hydrogen-phthalocyanin, also used as blue dye in ball pens, exhibits a strong magneto-resistance effect when trapped between electrodes, potentially opening up a variety of applications.

‘The immediate impact will be in new sensors for hard disks — but this is just the beginning,’ said lead researcher Prof Wulf Wulfhekel of the Karlsruhe Institute of Technology (KIT) in Germany.

‘The use of spin for information encoding has several advantages — it’s non-volatile so you don’t need power to save the state of your machine. If you switch off your computer and switch it back on again you don’t need to boot up.

‘And also the power consumption is far lower, so this has advantages for mobile devices especially.’

In electronic devices, information is traditionally stored and transmitted by the flow of electricity, based on the presence or absence of electrons, which create a binary code.

By contrast, in spintronics, information is stored and transmitted using another property of electrons: their spin.

The advantage is that the spin is maintained even when switching off current supply, which means that the component can store information without any energy consumption.

However, to increase data-storage density, miniaturisation is also important, as Prof Wulfhekel explained.

‘If you want to make things very small, typically you use lithography, but it’s hard to get reliable structures. In principle, to manufacture identical objects you have to have atomic precision and no one can do it at the moment.

‘But chemistry offers another approach — you can just synthesise molecules, they are all absolutely identical. The idea is to use these molecules as transistors, resistors and units of an electronic circuit.’

Scientists from KIT, the Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) in France and Chiba University in Japan contributed to the research that is published in the journal Nature Nanotechnology.

Scanning tunneling microscopy (50 x 50 nm2) of organic molecules. Coloring indicates variable spin orientation
Scanning tunnelling microscopy (50 x 50nm2) of organic molecules. The colouring indicates variable spin orientation