Beijing, March 14 (Xinhua) - Researchers at the Ames National Laboratory in the United States have identified the first unconventional superconductor in mineral form, with a chemical composition found in nature. The mineral called rhodium sulfide is one of only four minerals found in nature that can be cultivated as superconductors in the laboratory. Studies indicate its properties resemble those of high-temperature superconductors. This discovery deepens scientists' understanding of superconductivity and holds promise for more sustainable and economical superconductor-based technologies in the future. In the 1980s, scientists discovered unconventional superconductors, many of which have significantly higher critical temperatures than traditional superconductors. It was widely believed that unconventional superconductivity was not a natural phenomenon.
Rhodium sulfide is an intriguing mineral, partly due to its complex chemical formula (Rh17S15). It combines elements with extremely high melting points (such as Rhodium) with volatile elements (like sulfur).
Building upon this, researchers synthesized high-quality rhodium sulfide crystals. Within the Rh-S system, they discovered three new superconductors. Through meticulous measurements, they further established rhodium sulfide as an unconventional superconductor.
The research team employed three different testing methods to ascertain the superconducting properties of rhodium sulfide. The primary metric was the "London penetration depth," which determines the distance a weak magnetic field can penetrate through the bulk of a superconductor. In traditional superconductors, this length remains relatively constant at low temperatures. However, in unconventional superconductors, it varies linearly with temperature. This test revealed that rhodium sulfide exhibits behavior consistent with unconventional superconductors.
Another test involved introducing defects into the material, including bombarding it with high-energy electrons. This process dislodges ions from their positions, creating defects in the crystal structure. Such disorder affects the material's critical temperature. The tests also revealed that unconventional superconductors are highly sensitive to disorder, with the introduction of defects altering or suppressing the critical temperature, as well as affecting the material's critical magnetic field. In summary, the behavior of critical temperature and critical magnetic field in this unconventional superconductor aligns with predictions.
