Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Molecules take electronics for a spin


Researchers eager to use individual molecules as the components of ultra-small electronic circuits and computers have put a new spin on their ambitious goal.

They take advantage of a hitherto unexploited property of electric currents, called spin, to make molecular devices that operate under new rules. This fledgling form of electronics, called spintronics, could lead to computers that don’t forget anything when their power is turned off, and perhaps even to that ultra-powerful device, the quantum computer.

Jan Hendrik Schön of Bell Laboratories in New Jersey and co-workers have made a prototype spintronics device called a spin valve, in which the electrical current passes from one terminal to the other through individual carbon-based molecules1.

Previous spin valves were made from slabs of semiconductor, much as conventional transistors are made from silicon. But made from single molecules they could be much smaller than today’s miniaturized transistors on silicon chips. Circuits could then be more densely packed with devices and therefore more powerful.

Molecular electronics will probably complement rather than replace conventional semiconductor-based microelectronics. Making devices as small as single molecules will be very difficult. The electrical contacts for these devices "will always be larger than the dimensions of the molecules themselves," Schön cautions. This could limit the amount of miniaturization that is possible.

Up and down

Conventional devices such as transistors use electric fields to control how many electrons pass through them - in other words, how big the electric current is. A spin valve controls the current using magnetism.

It manipulates a property of every electron called spin. Spin takes one of two values: ’up’ or ’down’, and makes an electron magnetic

In a spin valve, layers of magnetic material act as a filter, letting through electrons with one spin orientation (up, say), and blocking those with oppositely oriented spins (down).

So information encoded in the electrons’ spins can be manipulated to perform computational tasks. The up/down orientation of spins is equivalent to the 1 and 0 of binary logic that computers use.

In a spin

To make their molecular spin valve, Schön and colleagues laid down a one-molecule-thick carpet of a substance called pentanethiol on top of a nickel film. The pentanethiol molecules stick out like bristles from the metal surface. A few bristles of a different molecule, benzene-1,4-thiol (BDT), conduct electrical current.

They then deposited a patchwork of thin nickel films on top, so the molecules were sandwiched between two layers of metal, which acted as electrical contacts.

These nickel films cover just a hundred thousand or so molecules each. On average, only one of these is a BDT molecule: this single molecule provides an electrical connection between the two layers of nickel. Because nickel is magnetic, it acts on a current via the electrons’ spins.

The researchers found that switching the direction in which the magnetic fields point in the top and bottom nickel layers alters the current. When the two fields are aligned, a lot of current passes through a single BDT molecule; when the fields point in opposite directions, the current drops because some electrons with the wrong spins are filtered out.

Wedge wires/b>

A team in Karlsruhe, Germany, led by Heiko Weber, have meanwhile shown that similar single-molecule ’wires’ spanning a tiny gap between two metal terminals act as weird wires. They conduct better in one direction than the other2.

These molecular wires are wedge shaped. In a normal metal wire this wouldn’t make any difference, showing how molecular-scale circuits could be designed using new principles.

  1. Schon, J. H., Emberly, E.G. & Kirczenow, G.A. A single molecular spin valve. Science, Published online, DOI:10.1126/science.1070563 (2002).
  2. Reichert, J. Driving current through single organic molecules. Physical Review Letters, 88, 176804 , (2002).

PHILIP BALL | © Nature News Service

More articles from Power and Electrical Engineering:

nachricht Neutrons pave the way to accelerated production of lithium-ion cells
20.03.2018 | Technische Universität München

nachricht Monocrystalline silicon thin film for cost-cutting solar cells with 10-times faster growth rate fabricated
16.03.2018 | Tokyo Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Science & Research
Overview of more VideoLinks >>>