Nav: Home

Efficient valves for electron spins

August 12, 2020

Researchers at the University of Basel in collaboration with colleagues from Pisa have developed a new concept that uses the electron spin to switch an electrical current. In addition to fundamental research, such spin valves are also the key elements in spintronics - a type of electronics that exploits the spin instead of the charge of electrons. The results were published in the scientific journal Communications Physics.

At some point, spintronics might become a buzzword that is as much a part of our vocabulary as electronics. The idea behind it is to use the angular momentum (spin) of an electron instead of the electrical charge. Researchers around the world have been pursuing this goal for many years. Spintronics promises numerous applications in information storage and processing, and could improve the energy efficiency of electronic devices. An important prerequisite is the efficient control and detection of electron spins.

A team of physicists around Professor Christian Schönenberger and Dr. Andreas Baumgartner from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel has now developed a new technique for spintronics in semiconductor devices. Researchers from the Instituto Nanoscienze-CNR in Pisa were also involved.

Nanomagnets are the key

For this purpose, the scientists form two small semiconductor islands (quantum dots) behind each other on a nanowire and generate magnetic fields in the quantum dots using nanomagnets. Using an external field, they are able to control these magnets individually and thus can determine whether a quantum dot allows electrons to pass with a spin directed upward (up) or downward (down). When two quantum dots are connected in series, a current only flows if both are set to "up" or both to "down". Ideally, no current flows if they are oriented in opposite directions.

Arunav Bordoloi, first author of the publication and PhD student in the Schönenberger team, found that this method produced a spin polarization close to the theoretical maximum. "With this technique, we can choose whether a single electron in a given spin state is allowed to enter or leave a quantum system - with an efficiency far greater than in conventional spin valves," he says.

"In recent years, researchers around the world found it a hard nut to crack to fabricate spin valves useful for nano- and quantum-electronic devices," says Dr. Andreas Baumgartner, who is supervising the project. "We have now succeeded in producing one."

Exploring new phenomena

The physicists were also able to show that the magnetic fields are localized to specific locations on the nanowire. "This technique should therefore allow us to study the spin properties of new phenomena typically too sensitive to magnetic fields, such as novel states at the ends of special superconductors," comments Dr. Baumgartner.

This new approach to spintronics should now enable direct measurements of spin correlations and spin entanglement and shed new light on many old and new physical phenomena. In the future, the concept could even prove useful in the quest to use electron spins as the smallest information unit (quantum bit) in a quantum computer.
-end-


University of Basel

Related Quantum Dots Articles:

'Growing' active sites on quantum dots for robust H2 photogeneration
Chinese researchers had achieved site- and spatial- selective integration of earth-abundant metal ions in semiconductor quantum dots (QDs) for efficient and robust photocatalytic H2 evolution from water.
New insights into the energy levels in quantum dots
Researchers from Basel, Bochum and Copenhagen have gained new insights into the energy states of quantum dots.
What a pair! Coupled quantum dots may offer a new way to store quantum information
Researchers at the National Institute of Standards and Technology (NIST) and their colleagues have for the first time created and imaged a novel pair of quantum dots -- tiny islands of confined electric charge that act like interacting artificial atoms.
Spinning quantum dots
A new paper in EPJ B presents a theoretical analysis of electron spins in moving semiconductor quantum dots, showing how these can be controlled by electric fields in a way that suggests they may be usable as information storage and processing components of quantum computers.
Controlling the charge state of organic molecule quantum dots in a 2D nanoarray
Australian researchers have fabricated a self-assembled, carbon-based nanofilm where the charge state (ie, electronically neutral or positive) can be controlled at the level of individual molecules.
Modified quantum dots capture more energy from light and lose less to heat
Los Alamos National Laboratory scientists have synthesized magnetically-doped quantum dots that capture the kinetic energy of electrons created by ultraviolet light before it's wasted as heat.
Using quantum dots and a smartphone to find killer bacteria
A combination of off-the-shelf quantum dot nanotechnology and a smartphone camera soon could allow doctors to identify antibiotic-resistant bacteria in just 40 minutes, potentially saving patient lives.
Synthesizing single-crystalline hexagonal graphene quantum dots
A KAIST team has designed a novel strategy for synthesizing single-crystalline graphene quantum dots, which emit stable blue light.
US Naval Research Laboratory 'connects the dots' for quantum networks
Researchers at the US Naval Research Laboratory developed a novel technique that could enable new technologies that use properties of quantum physics for computing, communication and sensing, which may lead to 'neuromorphic' or brain-inspired computing.
Quantum rebar: Quantum dots enhance stability of solar-harvesting perovskite crystals
Engineering researchers have combined two emerging technologies for next-generation solar power -- and discovered that each one helps stabilize the other.
More Quantum Dots News and Quantum Dots 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: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.