Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unveiling spiral magnetism

26.04.2010
Photoemission experiments shed light on the origin of an enigmatic type of magnetism in iron

Iron is the most useful magnet in our daily life. It is a ‘ferromagnet’ at room temperature and ambient pressure, but displays a variety of other magnetic properties that depend on its crystallographic structure.

Now, using a technique called angle-resolved photoemission spectroscopy (ARPES) on iron thin films, Jun Miyawaki from the RIKEN SPring-8 Center, Harima, and colleagues have uncovered the origins of a particular type of magnetic order, called the spin spiral (SS), which has eluded understanding despite extensive experimental and theoretical efforts.

Magnetism in iron is associated with the spin, or quantum angular momentum, of the valence electrons of its atoms. In a ferromagnet the spins are parallel to each other; however, a structural change in the position of atoms in the crystal matrix of iron can order the spins into a spin spiral, such that the angle between the spins varies periodically.

Miyawaki says he was shocked when he realized that the electronic structure of SS-ordered iron was still an open question; it is fundamental to understanding the material’s behavior.

To elucidate the origin of this magneto-structural behavior, Miyawaki and colleagues studied ultrathin iron films consisting of eight monolayers with a ferromagnetic bilayer at the top and six SS-ordered monolayers below. The researchers used the ARPES technique to bombard the SS layers with soft x-ray photons and knock out electrons. Then they measured the intensities and angles of the emitted electrons. This yielded information about the electrons' energy and momenta from which they constructed Fermi surfaces to characterize and predict various properties of iron.

Crucially, the researchers successfully mapped the energy-momentum relationship for electrons moving in- and out-of-plane of the iron film separately. Miyawaki notes that this required a concerted effort to develop the necessary instrumentation by his team at RIKEN and a team at the Japan Synchrotron Radiation Research Institute (JASRI).

The experimental results showed stark differences with respect to the symmetries of the in-plane and out-of-plane Fermi surfaces. A detailed analysis revealed that the SS magnetic order is directly linked to electrons ‘inhabiting’ specific regions of the out-of-plane Fermi surface, thus providing direct information about its origin on a microscopic level.

These findings not only provide vital clues to theoretical studies, but also suggest that iron thin films may be used in spintronics devices based on the spin-transfer torque phenomenon, Miyawaki notes. “Because right- and left-handed spin spirals exert a different spin-transfer torque on spin-polarized electrons, iron thin films could serve as memory devices,” he says.

The corresponding author for this highlight is based at the Excitation Order Research Team, RIKEN SPring-8 Center

Journal information

1. Miyawaki, J., Chainani, A., Takata, Y., Mulazzi, M., Oura, M., Senba, Y., Ohashi, H. & Shin, S. Out-of-plane nesting driven spin spiral in ultrathin Fe/Cu(001) films. Physical Review Letters 104, 066407 (2010)

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.rikenresearch.riken.jp/eng/research/6249
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>