This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Superconductors are materials that conduct electricity without electrical resistance when cooled below a specific critical temperature. These materials have proved promising for the development of various technologies, including medical imaging instruments, particle accelerators, ultrasensitive detectors and quantum processors.
Some superconductors are topological, which means their electronic states exhibit global patterns that remain unchanged under small disturbances. These materials can host Majorana bound states, localized quasiparticle excitations that could be leveraged to reduce errors made by quantum computers. In recent years, some physicists have been trying to identify materials that could exhibit what is known as spin-triplet superconductivity.
In this type of superconductivity, paired electrons have a combined spin of 1, as opposed to the spin of 0 observed in conventional superconductors. Spin-triplet superconductors could, in principle, support multiple superconducting phases and host robust Majorana states. This would make them particularly advantageous for the study of exotic quantum phenomena and the development of fault-tolerant quantum processors.
Researchers at Okayama University recently uncovered three superconducting phases characterized by distinct spin arrangements in the chromium-based material potassium chromium arsenide (K2Cr3As3). Their paper, published in Physical Review Letters, offers hints that this material could be a spin-triplet superconductor. "Spin-triplet superconductors are rare.
Although we previously discovered a spin-triplet state in the carrier-doped topological insulator CuxBi2Se3, and there are also suggestions of such states in some uranium-based compounds, several pieces needed to establish the field for applications are still missing," Guo-qing Zheng, senior author and professor of physics at Okayama University, told Phys.org. "One of them is multiple phases due to the internal degree of freedom. The objective of our study was to find multiple phases in K2Cr3As3." Building on their earlier efforts to identify spin-triplet superconductors, Zheng and his colleagues set out to examine the superconducting phases of a known chromium-based material.
They specifically examined K2Cr3As3, which has a superconducting transition temperature of 6.2 Kelvin and lacks magnetic order, meaning its magnetic moments do not settle into a fixed pattern. First, the researchers grew single K2Cr3As3 crystals using a high-temperature solution-growth technique. Subsequently, they examined the crystals using nuclear magnetic resonance, a technique that relies on magnetic fields and radio waves to probe atomic nuclei, offering insight into their local electronic environment.
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