Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists break the link between a quantum material's spin and orbital states

18.05.2020

The advance opens a path toward a new generation of logic and memory devices based on orbitronics that could be 10,000 times faster than today's

In designing electronic devices, scientists look for ways to manipulate and control three basic properties of electrons: their charge; their spin states, which give rise to magnetism; and the shapes of the fuzzy clouds they form around the nuclei of atoms, which are known as orbitals.


These balloon-and-disc shapes represent an electron orbital -- a fuzzy electron cloud around an atom's nucleus -- in two different orientations. Scientists hope to someday use variations in the orientations of orbitals as the 0s and 1s needed to make computations and store information in computer memories, a system known as orbitronics. A SLAC study shows it's possible to separate these orbital orientations from electron spin patterns, a key step for independently controlling them in a class of materials that's the cornerstone of modern information technology.

Credit: Greg Stewart/SLAC National Accelerator Laboratory


In SLAC experiments, scientists hit a quantum material with pulses of laser light (top) to see how this would affect zigzag patterns (middle) in its atomic lattice made by the spin directions of electrons (black arrows) and the orientations of electron orbitals (red balloon shapes). They were surprised to discover that the pulses disrupted the spin patterns while leaving the orbital patterns intact (bottom). This raises the possibility that spin and orbital states could be independently controlled to make much faster electronic devices.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

Until now, electron spins and orbitals were thought to go hand in hand in a class of materials that's the cornerstone of modern information technology; you couldn't quickly change one without changing the other.

But a study at the Department of Energy's SLAC National Accelerator Laboratory shows that a pulse of laser light can dramatically change the spin state of one important class of materials while leaving its orbital state intact.

The results suggest a new path for making a future generation of logic and memory devices based on "orbitronics," said Lingjia Shen, a SLAC research associate and one of the lead researchers for the study.

"What we're seeing in this system is the complete opposite of what people have seen in the past," Shen said. "It raises the possibility that we could control a material's spin and orbital states separately, and use variations in the shapes of orbitals as the 0s and 1s needed to make computations and store information in computer memories."

The international research team, led by Joshua Turner, a SLAC staff scientist and investigator with the Stanford Institute for Materials and Energy Science (SIMES), reported their results this week in Physical Review B Rapid Communications.

An intriguing, complex material

The material the team studied was a manganese oxide-based quantum material known as NSMO, which comes in extremely thin crystalline layers. It's been around for three decades and is used in devices where information is stored by using a magnetic field to switch from one electron spin state to another, a method known as spintronics. NSMO is also considered a promising candidate for making future computers and memory storage devices based on skyrmions, tiny particle-like vortexes created by the magnetic fields of spinning electrons.

But this material is also very complex, said Yoshinori Tokura, director of the RIKEN Center for Emergent Matter Science in Japan, who was also involved in the study.

"Unlike semiconductors and other familiar materials, NSMO is a quantum material whose electrons behave in a cooperative, or correlated, manner, rather than independently as they usually do," he said. "This makes it hard to control one aspect of the electrons' behavior without affecting all the others."

One common way to investigate this type of material is to hit it with laser light to see how its electronic states respond to an injection of energy. That's what the research team did here. They observed the material's response with X-ray laser pulses from SLAC's Linac Coherent Light Source (LCLS).

One melts, the other doesn't

What they expected to see was that orderly patterns of electron spins and orbitals in the material would be thrown into total disarray, or "melted," as they absorbed pulses of near-infrared laser light.

But to their surprise, only the spin patterns melted, while the orbital patterns stayed intact, Turner said. The normal coupling between the spin and orbital states had been completely broken, he said, which is a challenging thing to do in this type of correlated material and had not been observed before.

Tokura said, "Usually only a tiny application of photoexcitation destroys everything. Here, they were able to keep the electron state that is most important for future devices - the orbital state - undamaged. This is a nice new addition to the science of orbitronics and correlated electrons."

Much as electron spin states are switched in spintronics, electron orbital states could be switched to provide a similar function. These orbitronic devices could, in theory, operate 10,000 faster than spintronic devices, Shen said.

Switching between two orbital states could be made possible by using short bursts of terahertz radiation, rather than the magnetic fields used today, he said: "Combining the two could achieve much better device performance for future applications." The team is working on ways to do that.

###

Shen is now a postdoctoral researcher at Lund University in Sweden with a joint position with SIMES at SLAC. Scientists from the Advanced Light Source at DOE's Lawrence Berkeley National Laboratory; the Swiss Light Source at the Paul Scherrer Institute in Sweden; the University of Tokyo and University of Tsukuba in Japan; and the University of Chicago also contributed to this research. Both LCLS and the Advanced Light Source are DOE Office of Science user facilities, and major support for the study came from the DOE Office of Science. Turner's research was supported through the DOE Office of Science Early Career Research Program.

Citation: Lingjia Shen et al., Physical Review B Rapid Communications 101, 201103(R), 12 May 2020

Glennda Chui | EurekAlert!
Further information:
https://www6.slac.stanford.edu/news/2020-05-12-step-forward-orbitronics-scientists-break-link-between-quantum-materials-spin-and
http://dx.doi.org/10.1103/PhysRevB.101.201103

More articles from Physics and Astronomy:

nachricht Observation of intervalley transitions can boost valleytronic science and technology
18.05.2020 | University of California - Riverside

nachricht 'Hot and messy' entanglement of 15 trillion atoms
15.05.2020 | ICFO-The Institute of Photonic Sciences

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: When proteins work together, but travel alone

Proteins, the microscopic “workhorses” that perform all the functions essential to life, are team players: in order to do their job, they often need to assemble into precise structures called protein complexes. These complexes, however, can be dynamic and short-lived, with proteins coming together but disbanding soon after.

In a new paper published in PNAS, researchers from the Max Planck Institute for Dynamics and Self-Organization, the University of Oxford, and Sorbonne...

Im Focus: 'Hot and messy' entanglement of 15 trillion atoms

Quantum entanglement is a process by which microscopic objects like electrons or atoms lose their individuality to become better coordinated with each other. Entanglement is at the heart of quantum technologies that promise large advances in computing, communications and sensing, for example detecting gravitational waves.

Entangled states are famously fragile: in most cases even a tiny disturbance will undo the entanglement. For this reason, current quantum technologies take...

Im Focus: A new, highly sensitive chemical sensor uses protein nanowires

UMass Amherst team introduces high-performing 'green' electronic sensor

Writing in the journal NanoResearch, a team at the University of Massachusetts Amherst reports this week that they have developed bioelectronic ammonia gas...

Im Focus: Surgery Training with Robots and Virtual Reality

Joint press release from the University of Bremen and Chemnitz University of Technology

The insertion of hip implants places high demands on surgeons. To help young doctors practice this operation under realistic conditions, scientists from the...

Im Focus: Technology innovation for neurology: Brain signal measurement using printed tattoo electrodes

TU Graz researcher Francesco Greco has developed ultra-light tattoo electrodes that are hardly noticeable on the skin and make long-term measurements of brain activity cheaper and easier.

In 2015 Francesco Greco, head of the Laboratory of Applied Materials for Printed and Soft electronics (LAMPSe, http://lampselab.com/) at the Institute of Solid...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

13th AKL – International Laser Technology Congress: May 4–6, 2022 in Aachen – Laser Technology Live already this year!

02.04.2020 | Event News

 
Latest News

How to design city streets more fairly

18.05.2020 | Studies and Analyses

When proteins work together, but travel alone

18.05.2020 | Life Sciences

Emissions from road construction could be halved using today’s technology

18.05.2020 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>