Revealing the mysteries of superconductors: Ames Lab's new scope takes a closer look

May 09, 2018

The U.S. Department of Energy's Ames Laboratory has successfully demonstrated that a new type of optical magnetometer, the NV magnetoscope, can map a unique feature of superconductive materials that along with zero resistance defines the superconductivity itself.

That unique feature is the Meissner effect, which is the expulsion of the magnetic field during a material's transition to a superconducting state.

"The Meissner effect is the hallmark signature of a true superconductor, which separates it from a hypothetical perfect metal with zero resistance," said Ruslan Prozorov, an Ames Laboratory physicist who is an expert in superconductivity and magnetism at low temperatures. "That is fine in textbooks and in principle, but in real superconducting materials the Meissner effect is quite complicated. Robust screening of a magnetic field by a superconducting sample and Meissner expulsion upon cooling in a magnetic field can be confused. This effect is actually very weak and fragile and difficult to observe."

Until now, physicists have been able to observe the Meissner effect, but were unable to visualize its spatial distribution in the material and how that might vary between different superconducting compounds. Now it is possible to map unique and distinguishing features of the Meissner effect, using a very sensitive magnetoscope that takes advantage of the quantum state of a particular kind of an atomic defect, called nitrogen-vacancy (NV) centers, in diamond.

While the science behind using NV centers as sensors has been known, scientists at Ames Laboratory wanted to know if the technology could be harnessed for probing magnetic fields with unprecedented sensitivity and good spatial resolution and apply it to studying various magnetic and superconducting materials.

"This technique, which is minimally invasive and extremely sensitive, is implemented in an optical device that operates successfully while samples are at the low temperatures (4 degrees above absolute zero), which is necessary for quantum materials exploration. This was no trivial undertaking," said Prozorov.

A member of Prozorov's group, Ames Laboratory scientist Naufer Nusran, led the development of this unique set-up, and current work used diamond film with NV-centers implanted right beneath the surface to measure larger-scale variation of the magnetic fields. This is the first scientific paper published measuring the spatial distribution of the Meissner effect using an NV magnetoscope, proving that the technique works and is ready to be deployed to study even more complex problems.

Nusran also partnered with the Center for Nanoscale Materials, a DOE Office of Science user facility at Argonne National Laboratory, to design and fabricate the nanoscale pillars of diamond, each with a single NV center, for the construction of the magnetoscope, which took three years. Deployment of these sensors, now housed in Ames Laboratory's ultra-low noise Sensitive Instrumentation Facility (SIF), is the next step in research for the Prozorov group in the new lab.

It's already led to some big surprises.

Iron-based superconductors, considered some of the most robust, showed practically none of that "hallmark" Meissner effect.

"This is a big puzzle and we have no explanation," said Prozorov. "It will be an exciting new avenue in research to understand why this happens."

The research is further discussed in the paper,"Spatially-resolved study of the Meissner effect in superconductors using NV-centers-in-diamond optical magnetometry," authored by N.M. Nusran, K. R. Joshi, K Cho, M. A. Tanatar, W.R. Meier, S. L. Bud'ko, P.C. Canfield, Y. Liu, T.A. Lograsso, and R. Prozorov; and published in the New Journal of Physics.
-end-
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.

DOE/Ames Laboratory

Related Magnetic Field Articles from Brightsurf:

Investigating optical activity under an external magnetic field
A new study published in EPJ B by Chengping Yin, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China, aims to derive an analytical model of optical activity in black phosphorous under an external magnetic field.

Magnetic field and hydrogels could be used to grow new cartilage
Instead of using synthetic materials, Penn Medicine study shows magnets could be used to arrange cells to grow new tissues

Magnetic field with the edge!
This study overturns a dominant six-decade old notion that the giant magnetic field in a high intensity laser produced plasma evolves from the nanometre scale.

Global magnetic field of the solar corona measured for the first time
An international team led by Professor Tian Hui from Peking University has recently measured the global magnetic field of the solar corona for the first time.

Magnetic field of a spiral galaxy
A new image from the VLA dramatically reveals the extended magnetic field of a spiral galaxy seen edge-on from Earth.

How does Earth sustain its magnetic field?
Life as we know it could not exist without Earth's magnetic field and its ability to deflect dangerous ionizing particles.

Scholes finds novel magnetic field effect in diamagnetic molecules
The Princeton University Department of Chemistry publishes research this week proving that an applied magnetic field will interact with the electronic structure of weakly magnetic, or diamagnetic, molecules to induce a magnetic-field effect that, to their knowledge, has never before been documented.

Origins of Earth's magnetic field remain a mystery
The existence of a magnetic field beyond 3.5 billion years ago is still up for debate.

New research provides evidence of strong early magnetic field around Earth
New research from the University of Rochester provides evidence that the magnetic field that first formed around Earth was even stronger than scientists previously believed.

Massive photons in an artificial magnetic field
An international research collaboration from Poland, the UK and Russia has created a two-dimensional system -- a thin optical cavity filled with liquid crystal -- in which they trapped photons.

Read More: Magnetic Field News and Magnetic Field Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.