Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electron Spins Separated on a Semiconductor Surface

01.06.2012
New findings on the spin of electrons in semiconductor materials
In a recent publication, physicists of the University of Würzburg describe the spin architecture of an ultra-thin metal layer on a semiconductor for the first time. This represents yet another step towards high-performing super computers.

Würzburg physicists have determined the spin architecture of a semiconductor surface. For this purpose, electrons were displaced from the material by means of photo-excitation so that their spin orientation could be measured.
Graphics: Philipp Höpfner

The development of significantly faster computers might be feasible if the spin of electrons could be used as information carrier in data processing.

What is this electron spin? The spin gives the electron magnetic properties in addition to its electric charge. "You can imagine each electron as carrying a tiny elementary magnet, just like a compass needle," explains the Würzburg physicist, Jörg Schäfer.

In order to use the electron spin in electronics, thus implementing spintronics, it would be required to arrange the electrons flowing in a semiconductor chip by their spin state, i.e. to align their spin orientation. These elementary magnetic needles would have to keep this spin formation when traveling through the electronic device as so-called spin currents.

Trick allows spin separation without magnetic fields

It has been known for a long time that the spins can be manipulated by magnetic fields. However, this is not at all practicable for electronic applications. Therefore, the solid-state physicists devised an ingenious trick: An ultra-thin metal layer with a thickness of only one atom is vapor-deposited on a semi-conducting solid material. In this system, the electrons spontaneously sort themselves into two groups with opposite magnet needle orientation.

This effect is the more pronounced, the heavier the respective metal atoms are. "We wanted to produce and further examine this automatic spin separation in a model experiment," explains Professor Ralph Claessen. The Würzburg physicists decided to use gold as a particularly heavy metal, which they vapor-deposited in a wafer-thin layer on a semiconductor substrate consisting of Germanium.

Close interaction between theory and experiment

The experimental findings on the spin pattern correspond very accurately to the predictions developed by the Würzburg theoretical physicists working with Professor Werner Hanke. "We can create a mathematical model of the spin structure in the semiconductor, enabling us to make very accurate practical predictions with state-of-the-art computers," Hanke explains.

The spin pattern can be experimentally verified by means of photoemission spectroscopy. The relevant measurements were conducted at the Paul Scherrer Institute in Switzerland. In these measurements, the semiconductor surface with the gold layer is subjected to the particularly intensive X-ray radiation of a synchrotron. This causes electrons to get loose and fly out of the sample at various angles – depending on their spin – which can be spotted by detectors.

Two spin orientations clearly identified for the first time

"We observed a marked splitting of the spins into two groups with opposite orientation of the magnet needles and a special spin pattern," says Jörg Schäfer. Thus, all spins point out of the surface or into it. "The merit of this collaboration in the fields of theoretical and experimental physics lies in the fact that the three-dimensional spin pattern has been clarified for the first time," says Ralph Claessen. In particular, the results clearly show that the separation of the conduction electrons by their spin works well. Thus, they can be sent separately on their journey through the metal. This is new and important fundamental knowledge for spintronics.

The editor of the scientific journal "Physical Review Letters" was outright enthusiastic about these findings: The successful research from Würzburg is specially recommended for perusal to the knowledgeable readers of the journal as "Editor's Suggestion".

Study conducted within a DFG research group

The publication arose from Würzburg research group 1162, which has been funded by the German Research Foundation (DFG) with about three million euros since 2009. The group examines electronic quantum effects in nanostructures; Ralph Claessen is its spokesperson.

"Three-Dimensional Spin Rotations at the Fermi Surface of a Strongly Spin-Orbit Coupled Surface System", P. Höpfner, J. Schäfer, A. Fleszar, J. H. Dil, B. Slomski, F. Meier, C. Loho, C. Blumenstein, L. Patthey, W. Hanke, and R. Claessen, Physical Review Letters 108, 186801 (2012), DOI 10.1103/PhysRevLett.108.186801

Contact person

Prof. Dr. Ralph Claessen, Institute of Physics of the University of Würzburg, T +49 (0)931 31-85732, claessen@physik.uni-wuerzburg.de

Robert Emmerich | idw
Further information:
http://www.uni-wuerzburg.de

Further reports about: DFG Electron Semiconductor Spin Surface electron spin magnetic field

More articles from Physics and Astronomy:

nachricht New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology

nachricht Light rays from a supernova bent by the curvature of space-time around a galaxy
21.04.2017 | Stockholm University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

Im Focus: Quantum-physical Model System

Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms

Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...

Im Focus: Glacier bacteria’s contribution to carbon cycling

Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.

A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

New quantum liquid crystals may play role in future of computers

21.04.2017 | Physics and Astronomy

A promising target for kidney fibrosis

21.04.2017 | Health and Medicine

Light rays from a supernova bent by the curvature of space-time around a galaxy

21.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>