Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When old is new again

04.10.2010
A fundamental effect associated with electrons also occurs in non-charged particles—a potential boon for spintronics

Just as electronics revolutionized computing and communications technology, spintronics is touted to follow suit. This relatively new field involves manipulating the flow of a magnetism-related property called ‘spin’.

In magnons, a spintronic counterpart of electrons, Naoto Nagaosa from the RIKEN Advanced Science Institute (ASI) in Wako and his colleagues have observed an effect first seen with electrons over 130 years ago: the Hall effect1. The Hall effect is used in sensitive detectors, so the researchers believe their finding could lead to new applications for magnetic insulators.

The Hall effect arises because a charge-carrying particle such as an electron experiences a force perpendicular to its direction of motion as it moves through a magnetic field of a conducting material. The result is a build-up of charges of opposite signs on either side of the material, which creates a measureable electric field. Magnons, however, have no charge, so an analogous effect had never been observed previously.

“The Hall effect is one of the most fundamental phenomena in condensed matter physics,” explains Nagaosa. “It is important to study to what extent we can apply ideas from conventional electronics to spintronics.” Nagaosa, along with Yoshinori Tokura also from ASI, Yoshinori Onose and co-workers from The University of Tokyo, and Hosho Katsura from the University of California, Santa Barbara, USA, studied the magnetic and thermal properties of the insulating ferromagnet Lu2V2O7 at low temperatures. Rather than the electric field associated with the conventional effect, the Hall effect manifested in this material as a thermal conductivity gradient across the sample. This difference occurs because the magnons carry heat, rather than charge.

The researchers showed that the size of the effect is not proportional to the applied magnetic field, but has a maximum at relatively low fields. This supports the hypothesis that magnons, influenced by the relativistic interaction, are responsible because the number of magnons is known to be reduced at these low-level magnetic fields. They also observed that the conductivity gradient started to decrease at higher fields. This observation allowed Nagaosa and colleagues to rule out lattice vibrations, or phonons, as another possible underlying cause of the experimental results: a phonon-induced thermal conductivity gradient would be expected to continue to increase with magnetic field.

“According to our theoretical prediction, only certain types of the crystal structure show this magnon Hall effect,” says Nagaosa. “To confirm this theory, we next aim to check that the phenomenon is absent in more conventional structures such as a cubic lattice.”

The corresponding author for this highlight is based at the Theoretical Design Team, RIKEN Advanced Science Institute

Journal information

1. Onose, Y., Ideue, T., Katsura, H., Shiomi, Y., Nagaosa, N. & Tokura, Y. Observation of the magnon Hall effect. Science 329, 297–299 (2010)

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6400
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Long-lived storage of a photonic qubit for worldwide teleportation
12.12.2017 | Max-Planck-Institut für Quantenoptik

nachricht Telescopes team up to study giant galaxy
12.12.2017 | International Centre for Radio Astronomy Research

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>