New quantum criticality discovered in superconductivity

A greater understanding of the link between magnetism and unconventional superconductivity.

Scientists at the U.S. Department of Energy’s Ames Laboratory discovered a new quantum criticality in a superconducting material using solid-state nuclear magnetic resonance (ssNMR) techniques. According to scientists, the discovery may lead to getting a detailed insight into the link between magnetism and unconventional superconductivity.

Most iron-arsenide superconductors show both magnetic and structural (or nematic) advances, making it difficult to comprehend the job they play in superconducting states. In any case, a compound of calcium, potassium, iron, and arsenic, and doped with a little amount of nickel, CaK(Fe1-xNix)4As4, first made at Ames Laboratory, has been found to show another magnetic state called a hedgehog turn vortex precious stone antiferromagnetic state without nematic changes.

Yuji Furukawa, a senior scientist at Ames Laboratory and a professor of Physics and Astronomy at Iowa State University said, “Spin or nematic fluctuations can be considered to play an important role for unconventional superconductivity. th this particular material, we were able to examine only the magnetic fluctuations, and NMR is one of the most sensitive techniques for examining them.”

“Using 75As NMR, we discovered that CaKFe4As4 is located at a hedgehog spin-vortex crystal antiferromagnetic quantum critical point which is avoided due to superconductivity. The discovery of the magnetic quantum criticality without nematicity in CaK(Fe1−xNix)4As4 suggests that the spin fluctuations are the primary driver of superconductivity.”

Paul Canfield, a senior scientist at Ames Laboratory said, “This is a new type of magnetic order. You have this interesting interaction between superconductivity and magnetism from high temperatures in the normal state. This gives us some sense that this high-temperature superconductivity may be coming from this near quantum critical antiferromagnetic transition.”

The study is published in journal Physical Review Letters.

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