Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Demagnetization by rapid spin transport

28.01.2013
For purposes of their research, the scientists irradiated two separate layered systems with ultrashort laser pulses on the order of just one hundred femtoseconds (10-15 s).

One sample consisted essentially of a single thin layer of ferromagnetic nickel. By contrast, a second sample of this same nickel material was coated with a non-magnetic layer of gold.

Only a mere 30 nanometers (10-9 m) thick, the gold layer swallowed up the lion's share of the laser light so that barely any light ended up reaching the nickel layer. In spite of this, the nickel layer's magnetization rapidly dissipated shortly after the laser pulse entered each sample. However, in the case of the gold-coated sample, the researchers recorded a split-second delay. The observations were based on measurements obtained using circularly polarized femtosecond x-ray pulses at BESSY II, Berlin's own electron storage ring, with the help of the femtoslicing beamline.

"This allowed us to demonstrate experimentally that during this process, it isn't the light itself that is responsible for the ultrafast demagnetization but rather hot electrons, which are generated by the laser pulse," explains Andrea Eschenlohr. Excited electrons are able to rapidly move across short distances - like the ultra-thin gold layer. In the process, they also deliver their magnetic moment (their "spin") to the ferromagnetic nickel layer, prompting the breakdown of the latter's magnetic order. "Actually, what we had hoped to see is how we might be able to influence the spin using the laser pulse," explains Dr. Christian Stamm, who heads the experiment. "The fact that we ended up being able to directly observe how these spins migrate was a complete surprise to everyone."

Laser pulses are thus one possibility to generate "spin currents" where the spin is transferred in place of an electric charge. This observation is relevant for spintronics research where scientists design new devices from magnetic layered systems, which perform calculations based on spins rather than electrons, enabling them to very quickly process and store information while at the same time saving energy.

Dr. Eschenlohr concluded her doctoral work at HZB, in the context of which she generated the results described above, in late 2012. As of January of this year, Dr. Eschenlohr is a scientific associate at University of Duisburg-Essen.

The paper "Ultrafast spin transport as key to femtosecond demagnetization" will be published on 27. January 2013, 18:00 London time (GMT), in Nature Materials with doi: 10.1038/nmat3546.

For additional information please contact Dr. Christian Stamm, Methods and Instrumentation for Synchrotron Radiation Research
Phone: +49 (0)30-8062-14887
E-mail: christian.stamm@helmholtzberlin.de

Dr. Andrea Eschenlohr | EurekAlert!
Further information:
http://www.helmholtzberlin.de

More articles from Materials Sciences:

nachricht Breakthrough in nanoresearch - Quantum chains in graphene nanoribbons
09.08.2018 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht UNH Researchers find seed coats could lead to strong, tough, yet flexible materials
08.08.2018 | University of New Hampshire

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>