Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers develop technique to control and measure electron spin voltage

14.07.2017

New tool may provide insight into spintronic devices and exotic physics

Information technologies of the future will likely use electron spin -- rather than electron charge -- to carry information. But first, scientists need to better understand how to control spin and learn to build the spin equivalent of electronic components, from spin transistors, to spin gates and circuits.


Researchers used atomic-size defects in diamonds to detect and measure magnetic fields generated by spin waves.

Image courtesy of Peter and Ryan Allen/Harvard University

Now, Harvard University researchers have developed a technique to control and measure spin voltage, known as spin chemical potential. The technique, which uses atomic-sized defects in diamonds to measure chemical potential, is essentially a nanoscale spin multimeter that allows measurements in chip-scale devices.

The research is published in Science.

"There is growing interest in insulating materials that can conduct spin," said Amir Yacoby, Professor of Physics in the Department of Physics and of Applied Physics at Harvard John A. Paulson School of Engineering and Applied Sciences and senior author of the paper. "Our work develops a new way to look at these spins in materials such as magnets."

In conducting materials, electrons can carry information by moving from point A to point B. This is an electric current. Spin, on the other hand, can propagate through insulating materials in waves -- each electron standing still and communicating spin to its coupled neighbor, like a quantum game of telephone.

To drive these waves from point A to point B, the researchers needed to develop a technique to increase the spin chemical potential -- spin voltage -- at a local level.

"If you have a high chemical potential at location A and a low chemical potential at location B, spin waves start diffusing from A to B," said Chunhui Du, a postdoctoral fellow at the Department of Physics and co-first author of the paper. "This is a very important concept in spintronics, because if you are able to control spin-wave transport, then you can use these spin waves instead of electrical current as carriers of information."

The researchers used two spin-wave injection methods: in the first, they applied fast-oscillating, microwave magnetic fields to excite spin waves. In the second, they converted an electrical current into spin waves using a platinum metal strip located at one end of the magnet.

"What's remarkable is that this material is an insulator; it doesn't conduct any current and still you can send information in the form of spin waves through it," said Toeno Van der Sar, a postdoctoral fellow at the Department of Physics and co-first author of the paper. "Spin waves are so promising because they can travel for a long time without decaying, and there is barely any heat produced because you don't have moving electrons."

Once the team injected spin waves into the material, the next step was to figure out how to measure information about those waves. The researchers turned to nitrogen-vacancy (NV) defects in diamonds. These defects -- in which one carbon atom in a diamond is replaced with a nitrogen atom and a neighboring atom is removed -- can be used to detect minute magnetic fields.

The researchers fabricated tiny rods of diamond containing NV centers and placed them nanometers above the sample. As the spin waves move through the material, they generate a magnetic field, which is picked up by the NV center.

Based on NV-center measurements, researchers can now figure out the spin chemical potential, the number of spin waves, how they are moving through the material and other important insights.

"The nice thing about this technique is that it's very local," said Van der Sar. "You can do these measurements just a few nanometers above the sample, which means that you can spatially study the chemical potential in a chip-scale spin-wave device, for, let's say, a spin-wave computer. This is not possible with some of the other state-of-the-art techniques."

This system could also offer a glimpse into more exotic physics such as the spin-wave Hall effect, or show that spin-wave transport is hydrodynamic.

"The principle we use to control and measure the spin chemical potential is quite general. It opens ways to study more exotic spin phenomena in novel materials and aids the development of new spintronic devices," said Du.

###

This research was supported in part by the Gordon and Betty Moore Foundation's Emergent Phenomena in Quantum Systems (EPiQS) Initiative, the Multidisciplinary University Research Initiative (MURI) Quibit Enabled Imaging, Sensing, and Metrology (QuISM) project and the Army Research Office.

Media Contact

Leah Burrows
lburrows@seas.harvard.edu
617-496-1351

 @hseas

http://www.seas.harvard.edu/ 

Leah Burrows | EurekAlert!

Further reports about: defects diamonds electron spin magnetic fields materials waves

More articles from Physics and Astronomy:

nachricht Comet or asteroid? Hubble discovers that a unique object is a binary
21.09.2017 | NASA/Goddard Space Flight Center

nachricht First users at European XFEL
21.09.2017 | European XFEL GmbH

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: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Comet or asteroid? Hubble discovers that a unique object is a binary

21.09.2017 | Physics and Astronomy

Cnidarians remotely control bacteria

21.09.2017 | Life Sciences

Monitoring the heart's mitochondria to predict cardiac arrest?

21.09.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>