Nav: Home

Ferromagnetic nanoparticle systems show promise for ultrahigh-speed spintronics

March 28, 2019

WASHINGTON, D.C., March 28, 2019 -- In the future, ultrahigh-speed spintronics will require ultrafast coherent magnetization reversal within a picosecond -- one-trillionth of a second. Spintronics centers on an electron's spin and magnetic moment in solid-state devices. While this may eventually be achieved via irradiation with a nearly monocyclic terahertz pulse, the small change of magnetization, or modulation, it generates has so far prevented any practical application of this technique.

Generally, the "magnetic field" component of a terahertz pulse is considered to be the origin of the coherent terahertz response of the magnetization. But, as a group of University of Tokyo researchers previously discovered, the "electric field" component of a terahertz pulse plays a key role in the terahertz magnetization modulation of semiconductor-based ferromagnetic materials.

Now the group reports in the journal Applied Physics Letters, from AIP Publishing, that their initial discovery inspired them to explore ferromagnetic nanoparticles embedded within a semiconductor. Their theory was that the electric field of the terahertz pulse could be effectively applied to each nanoparticle due to the small energy loss of the terahertz pulse during its propagation through a semiconductor.

"Until now, ferromagnetic metal films have been used for studies on the terahertz modulation of the magnetization," said Shinobu Ohya, an associate professor at the University of Tokyo. "The modulation ratio reported so far has typically been less than ~1 percent of the saturation magnetization."

To test their theory, the group used a 100-nanometer-thick semiconductor gallium arsenide (GaAs) film embedded with ferromagnetic manganese arsenide (MnAs) nanoparticles. "The small energy loss of the terahertz pulse during the propagation in our film allows it to penetrate the film. This means that the strong terahertz electric field -- with a maximum intensity of 200 kilovolts/centimeter -- is uniformly applied to all of the ferromagnetic nanoparticles," said Ohya. "This strong electric field induces the large magnetization modulation via the modulation of the carrier density in the MnAs nanoparticles, thanks to the spin-orbit interaction."

The researchers succeeded in obtaining a large modulation of up to 20 percent of the saturation magnetization, and also concluded that the electric field component of the terahertz pulse plays a key role in the large modulation.

"Our results will lead to an ultrafast coherent magnetization reversal within a picosecond, which will be an essential technique for ultrahigh-speed spintronics," Ohya said. "Ferromagnetic nanoparticle systems are extremely promising for high-speed magnetization switching using terahertz pulses."
-end-
The article, "Large terahertz magnetization response in ferromagnetic nanoparticles," is authored by Tomoaki Ishil, Hiromichi Yamakawa, Toshiki Kanaki, Tatsuya Miyamoto, Noriaki Kida, Hiroshi Okamotoa, Masaaki Tanaka and Shinobu Ohya. It was published in Applied Physics Letters on Feb. 12, 2019 (DOI: 10.1063/1.5088227). The article can be accessed at http://aip.scitation.org/doi/full/10.1063/1.5088227.

ABOUT THE JOURNAL

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See http://apl.aip.org.

American Institute of Physics

Related Nanoparticles Articles:

Nanoparticles: Acidic alert
Researchers of Ludwig-Maximilians-Universitaet (LMU) in Munich have synthesized nanoparticles that can be induced by a change in pH to release a deadly dose of ionized iron within cells.
3D reconstructions of individual nanoparticles
Want to find out how to design and build materials atom by atom?
Directing nanoparticles straight to tumors
Modern anticancer therapies aim to attack tumor cells while sparing healthy tissue.
Sweet nanoparticles trick kidney
Researchers engineer tiny particles with sugar molecules to prevent side effect in cancer therapy.
A megalibrary of nanoparticles
Using straightforward chemistry and a mix-and-match, modular strategy, researchers have developed a simple approach that could produce over 65,000 different types of complex nanoparticles.
Dialing up the heat on nanoparticles
Rapid progress in the field of metallic nanotechnology is sparking a science revolution that is likely to impact all areas of society, according to professor of physics Ventsislav Valev and his team at the University of Bath in the UK.
Illuminating the world of nanoparticles
Scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have developed a light-based device that can act as a biosensor, detecting biological substances in materials; for example, harmful pathogens in food samples.
What happens to gold nanoparticles in cells?
Gold nanoparticles, which are supposed to be stable in biological environments, can be degraded inside cells.
Lighting up cardiovascular problems using nanoparticles
A new nanoparticle innovation that detects unstable calcifications that can trigger heart attacks and strokes may allow doctors to pinpoint when plaque on the walls of blood vessels becomes dangerous.
Cutting nanoparticles down to size -- new study
A new technique in chemistry could pave the way for producing uniform nanoparticles for use in drug delivery systems.
More Nanoparticles News and Nanoparticles Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.