Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetism at Nanoscale

04.08.2015

Ames Laboratory physicists using N-V center optical magnetoscope to understand new magnetic nanomaterials

As the demand grows for ever smaller, smarter electronics, so does the demand for understanding materials’ behavior at ever smaller scales. Physicists at the U.S. Department of Energy’s Ames Laboratory are building a unique optical magnetometer to probe magnetism at the nano- and mesoscale.


U.S. Department of Energy's Ames Laboratory

Physicists at the U.S. Department of Energy's Ames Laboratory are using an NV-magnetoscope to make use of nitrogen-vacancy centers in diamond to sense extremely weak magnetic fields in nano- and mesoscale magnetic materials.

The device, called a NV-magnetoscope, makes use of the unique quantum mechanical properties of nitrogen-vacancy (NV) centers in diamond. The low temperature NV-magnetoscope setup incorporates a confocal microscope (CFM) and an atomic-force scanning microscope (AFM). The NV-magnetoscope will be able to sense the extremely weak magnetic fields of just a handful of electrons with the spatial resolution of about 10 nanometers.

“We want to determine magnetic textures more precisely than ever before, at smaller scales than ever before,” said Ames Laboratory physicist Ruslan Prozorov. “Our hope is to understand nano- and mesoscale magnetism, learn how to control it and, eventually, use that to create a new generation of technologies.”

NV Centers

Usually, diamonds are most valued when they’re perfect and big. But physicists see special value in diamonds’ tiny flaws: a certain kind of imperfection, called a nitrogen vacancy (NV) center, serves as a very sensitive sensor of the magnetic field exactly at the location of the NV center. NV centers are created when a carbon atom is substituted with a nitrogen atom. When there is a missing atom or a “vacancy” nearby the nitrogen atom, this forms the stable pair called the nitrogen-vacancy center.

What makes NV centers so useful? Physicists know a lot about how NV centers work. (In fact, Ames Laboratory is home to one of the world’s leading experts on NV centers, theoretical physicist Viatcheslav Dobrovitski.) Scientists know how much energy it takes to push electrons from the lowest energy, or ground state, to an excited state and, more importantly, how much energy will be released in form of a red photon when the electron relaxes back to the low-energy level. NV centers’ well-defined quantum energy levels are extremely sensitive to a magnetic field. This sensitivity enables the NV-magnetoscope to detect very small magnetic fields – such as that produced by nano- and mesoscale magnetic materials, for example – by reading optical fluorescence emitted by the excited NV centers.

Green Laser Light Excites the NV Center

“Electrons start at low-energy quantum states. And the green laser light ‘kicks’ them to a high excited state. The rules of quantum mechanics say that those electrons must return back to the lower energy level. If an electron was excited from a non-magnetic level, it always emits red light. However, if it was excited from one of the low-energy magnetic levels, it most likely relaxes back without any emission.

Microwave radiation is used to scramble electrons between low-energy magnetic and non-magnetic states, reaching maximum population of the magnetic states when the interlevel energy difference matches microwave energy. Therefore, by scanning microwave frequency, red fluorescence will cause double-dip spectra, corresponding to two magnetic energy levels, split by the magnetic field (called Zeeman splitting). The distance between the dips is proportional to the magnetic field at the location of an NV center,” said Prozorov

Detector Counts Red Photons

As excited electrons lose energy and return back to the low energy state, they emit red light. A detector counts the number of red photons.

NV Centers “Feel” Sample’s Magnetic Fields

A roughly 100-nanometer-long diamond containing NV centers is attached to the AFM tip. The confocal microscope focuses on a single NV center, collecting red photons only from one tiny area while blocking out outside “noise.” The sample of interest is scanned below the NV center. The NV center “feels” the variation of magnetic fields produced by the sample.

“When the sample of interest is brought close enough to an NV center, the sample’s magnetic field is extended to the location of the NV center and affects the center’s quantum energy levels. By accurately moving the sample in two dimensions close to the NV center, we can reconstruct the magnetic field intensity map produced by the sample. This, in turn, gives access to the magnetic properties of the sample itself,” said Prozorov.

This work was supported by the DOE Office of Science.

Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Contact Information
Breehan Gerleman Lucchesi
Communications specialist
breehan@ameslab.gov
Phone: 515-294-9750

Breehan Gerleman Lucchesi | newswise
Further information:
http://www.ameslab.gov

More articles from Materials Sciences:

nachricht New material could lead to erasable and rewriteable optical chips
07.12.2016 | University of Texas at Austin

nachricht Porous crystalline materials: TU Graz researcher shows method for controlled growth
07.12.2016 | Technische Universität Graz

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>