Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breakthrough for information technology using Heusler materials

13.06.2014

Basis for future development of very high performance spintronic components

It is the breakthrough that physicists and chemists around the world have long anticipated and it will play a pivotal role in information technology in coming years. Researchers at Johannes Gutenberg University Mainz (JGU) have managed, for the first time, to directly observe the 100 percent spin polarization of a Heusler compound. Heusler alloys are composed of several metallic elements arranged in a lattice structure.

They are among those materials that potentially can be used for ever smaller data storage components with ever greater storage capacity. However, doubts have been recently expressed as to whether Heusler materials are actually suitable for this purpose.

The physicists at Mainz University have now demonstrated that the Heusler compound Co2MnSi has the necessary electronic properties. The project was conducted in collaboration with theoretical physicists and chemists at the Ludwig-Maximilians-Universität (LMU) München and the Max Planck Institute for Chemical Physics of Solids (MPI-CPfS) in Dresden.

The results have recently been published in the online scientific journal Nature Communications. The findings provide the cornerstone for the future development of high-performance spintronic devices using Heusler materials. The potential applications include hard disk reader heads and non-volatile storage elements.

Electrons act as charge carriers in metals and semi-conductors. However, they not only have a charge that is relevant in conventional electronics but also a magnetic moment, the spin, which can be thought of as originating from a rotation of the electron around its own axis. Spin-based electronics, or spintronics, is widely seen as an integral part of information technology of the future, but innovative materials are required if this concept is to be appropriately realized. Potential applications are, for example, hard disk drive read heads and non-volatile magnetic memory.

One decisive parameter in this connection is the spin polarization, i.e., the degree of parallel orientation of the spins of the electrons that transport the charge. The ideal material will have the maximum possible spin polarization, i.e., the spins of the maximum number of current carrying electrons point in the same direction.

The Mainz physicists have been able to produce the first experimental proof of almost complete spin polarization at room temperature in the metallic Heusler alloy Co2MnSi. "This class of materials has long been under investigation and there is substantial theoretical evidence for the required electronic properties of Heusler compounds but no single experiment has previously been able to confirm 100 percent spin polarization at room temperature," explained PD Dr. Martin Jourdan of JGU, the primary author of the study.

Encouraging results had already been obtained at very low temperatures of –269 degree Celsius. Crucial for potential applications of the compound Co2MnSi, consisting of cobalt, manganese, and silicon, is an additional aspect of the experimental findings made by the scientists: They observed the high spin polarization at the material's surface.

Professor Claudia Felser, who established the field of research into half-metallic Heusler materials 15 years ago, sees the results of the study as a long-awaited breakthrough. "Direct experimental evidence of 100 percent spin polarization has finally been found”, said Felser, Director of the Max Planck Institute for Chemical Physics of Solids in Dresden. “This represents a major step forward when it comes to the development of new spintronic devices."

The successful experiments were based on the preparation of samples with extreme precision. For this the crystalline structure of the Heusler compound had to be perfectly ordered, in particular at the material's surface, which was realized in Mainz by means of thin-film preparation in ultra-high vacuum. The spin polarization was then measured using photo electron spectroscopy and could be explained in collaboration with the theoreticians at LMU and the MPI-CPfS as the result of a special combination of bulk and surface properties of the compound.

"It is not merely a breakthrough in the search for new spintronic materials but also in the interplay between theory and experiment," remarked Jourdan. "We were able to show that perfectly prepared materials actually have the properties that have been theoretically predicted." Heusler materials are being researched globally, particularly in Japan, Germany, and the USA. At JGU they are the subject of a core research unit that is part of the Graduate School of Excellence “Materials Science in Mainz” (MAINZ) and the Center for Innovative and Emerging Materials (CINEMA).

The LMU physicochemists PD Dr. Jan Minar, Professor Jürgen Braun, and Professor Hubert Ebert provided the theoretical framework for this study. "The spectroscopic calculations were carried out using a so-called one-step model," explained Minar, a member of Ebert's team that developed the theoretical program. "Such a combination of electronic structure and theoretical photoemission calculations made direct comparison with the corresponding experimental data possible, which in turn was essential to interpreting the 100 percent spin polarization that was measured."

Image:
http://www.uni-mainz.de/bilder_presse/08_physik_komet_heusler_verbindung.jpg
Diagram illustrating the principle of spin-resolved photoemission spectroscopy of thin Heusler films
ill./©: Martin Jourdan, JGU

Publication:
Martin Jourdan et al.
Direct observation of half-metallicity in the Heusler compound Co2MnSi
Nature Communications, 30 May 2014
DOI:10.1038/ncomms4974

Further information:
PD Dr. Martin Jourdan
Institute of Physics
Johannes Gutenberg University Mainz (JGU)
D 55099 Mainz, GERMANY
phone +49 6131 39-23635
fax +49 6131 39-24076
e-mail: jourdan@uni-mainz.de
http://www.klaeui-lab.physik.uni-mainz.de/505.php

Weitere Informationen:

http://www.klaeui-lab.physik.uni-mainz.de/ ;
http://www.nature.com/ncomms/2014/140530/ncomms4974/full/ncomms4974.html ;
http://www.cup.uni-muenchen.de/dept/ch/pc/ebert.php ;
http://www.cpfs.mpg.de/inorganic_chemistry

Petra Giegerich | idw - Informationsdienst Wissenschaft

Further reports about: Breakthrough Communications JGU LMU Physics materials metallic photoemission polarization spectroscopy structure

More articles from Information Technology:

nachricht Miniscule Mirrored Cavities Connect Quantum Memories
24.06.2015 | Department of Energy, Office of Science

nachricht SASER-Siegfried – Record-breaking Transmission Field Trial
24.06.2015 | EURESCOM European institute for research and strategic studies in telecommunications

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

Im Focus: Thousands of Droplets for Diagnostics

Researchers develop new method enabling DNA molecules to be counted in just 30 minutes

A team of scientists including PhD student Friedrich Schuler from the Laboratory of MEMS Applications at the Department of Microsystems Engineering (IMTEK) of...

Im Focus: Bionic eye clinical trial results show long-term safety, efficacy vision-restoring implant

Patients using Argus II experienced significant improvement in visual function and quality of life

The three-year clinical trial results of the retinal implant popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of...

Im Focus: Lasers for Fast Internet in Space – Space Technology from Aachen

On June 23, the second Sentinel mission was launched from the space mission launch center in Kourou. A critical component of Aachen is on board. Researchers at the Fraunhofer Institute for Laser Technology ILT and Tesat-Spacecom have jointly developed the know-how for space-qualified laser components. For the Sentinel mission the diode laser pump module of the Laser Communication Terminal LCT was planned and constructed in Aachen in cooperation with the manufacturer of the LCT, Tesat-Spacecom, and the Ferdinand Braun Institute.

After eight years of preparation, in the early morning of June 23 the time had come: in Kourou in French Guiana, the European Space Agency launched the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

3D Plasmonic Antenna Capable of Focusing Light into Few Nanometers

30.06.2015 | Physics and Astronomy

X-rays and electrons join forces to map catalytic reactions in real-time

30.06.2015 | Physics and Astronomy

A polarizing view

30.06.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>