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Scientists measure the exact edge between superconductors and magnetic states

Feb 28, 2019

(Nanowerk News) Energy The US scientists from Ames Laboratory have developed a method of "precise edge" or a measurement of the occurrence when magnetic fields enter the superconducting material (Applied Physical Review, "Measurement of the critical area of ​​superconductors to measure Nitrogen-Vacancy optical diameter magnetometrics").

Knowledge of this section – called critical ground below – The main task is to dissolve the difficulties that prevent the widespread use of superconductivity in new technologies.optical magnetometerAmes Laboratory scientists have developed a new optical magnetometer using the quantum state of certain atomic gaps in the diamond, called nitrogen gaps (NV) to detect magnetic field penetration. (Image: Ames Laboratory)

In physics of condensed matter, scientists distinguish between superconductors. When placed in a magnetic field, the critical top field is strong and the material is completely destroyed by superconductors. The Meissner effect can be thought to be its opposite, when the material becomes a superconducting state, it expels a magnetic field inside the interior, so the zero length (at least a micrometer) is called the length characteristic of the penetration of London.

But what about two gray areas? Almost all superconductors are type II, in larger magnetic fields, they do not show Meissner's full effect. Instead, they develop a mixed state with quantum magnetic vortices Abrikosov vortices – Material compacted thread, forming a two-dimensional vortex grid and significantly influencing the behavior of superconductors. Most importantly, these vortices emit electrical currents around and eliminate superconductivity.

When it is called the smallest critical area below, a superconductor is called a starting point. This makes measurement difficult due to the distortion of the magnetic field near the edge of the sample. However, knowledge of this field is necessary to control and control superconductors in applications.

"The boundary line, that is, the value of the value of a magnetic field depends on the value, Abrikosov's presence of the sting changes the behavior of superconducting," said Ruslan Prozorov, a physicist at Ames Laboratory, superconductivity and magnetism. "Many applications that we want to use for superconductivity increase the phase of this whirlwind."

To validate the innovative technique developed to measure this boundary line, Prozorov and his team have tested three superconducting materials. Recently, they have been using an optical magnetometer, taking advantage of the quantum state of a certain atomic error occurring at a nitrogen gap (NV) at the nucleus of the nitrogen gap (NV). Thanks to a very sensitive tool, scientists allow measuring small detours in magnetic signals at the edge of the sample that penetrates into eight.

"Our method is not an invasive one, it has a much better resolution and precise resolution than previously used," said Prozorov.

Additionally, the theoretical calculations, along with Vladimir Kogan's Ames laboratory science, were allowed to extract the values ​​of small areas of the area, depending on the phenomenon of penetration of the vortex.

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