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Measuring the properties of superconducting materials in magnetic fields at temperatures near absolute zero is difficult, but it is necessary to understand their quantum properties.
How cold? Less than 0.05 Kelvin (-272 ° C).
"For many modern (quantum) materials, to study the details of their quantum mechanical behavior well, you have to be colder, and it would be colder than previously thought," he said. said Ruslan Prozorov, a physicist at the Ames Laboratory of the US Department of Energy. specializes in the development of an instrumentation that measures exactly what kind of things.
Prozorov and his research team have developed a method for measuring the magnetic properties of superconducting and magnetic materials that exhibit unusual quantum behavior at very low temperatures in high magnetic fields. This method is used to study quantum critical behavior, superconductivity mechanisms, magnetic frustrations and phase transitions in materials, many of which were first manufactured at the Ames laboratory.
To do this, they installed a tunnel resonator, an instrument for accurately measuring magnetic properties by radiofrequency, in a dilution refrigerator, a cryogenic device capable of cooling samples in the indicated temperature range in milli-Kelvin. Although this has already been done before, previous work did not have the ability to apply large static magnetic fields, which is crucial for the study of quantum materials.
The Prozorov Group strives to overcome the technical difficulties associated with maintaining high resolution magnetic measurements, while reaching extremely cold temperatures up to 0.05 K and magnetic fields up to 14 tesla. A similar circuit had already been used in a very high magnetic field (60 T) when the team had conducted the experiments at the Los Alamos National Laboratory.
"When we installed the dilution refrigerator for the first time, the joke said that my lab had the coldest temperatures in Iowa," said Prozorov, who conducts research in conditions where the Midwestern winters are not a matter of laughing. "But we were not doing this just for fun, to see how cold we could be in. Many of the unusual quantum properties of materials can only be discovered at these extremely low temperatures."
The group studied the symmetry of pairing in several unconventional superconductors, mapped a very complex phase diagram in a field-induced quantum critical behavior system, and recently revealed the very unusual properties of a spin-ice system ", which would be impossible without this assembly," said Prozorov.
Source of the story:
Material provided by DOE / Ames Laboratory. Note: Content can be changed for style and length.
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