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A laser-guided path to diamond superconductors?


A study of boron in diamond films is interesting, but claims of potential superconducting properties may be premature, writes Andrew Stapleton.


A diamond, recently.
Mina De La O / Getty

Besides glittering beautifully in the sun, diamonds have another attractive property: they can become superconductive. Superconductivity occurs when a material has zero electrical resistance and is normally only seen when the material is chilled to temperatures very close to absolute zero (around –273 °C), which severely limits the use of superconductors in commercial applications.

Scientists from India and Israel conducted the first systematic study to understand how doping diamond with boron effects its ability to become superconducting. They reported their findings in Applied Physics Letters.

The scientists fabricated a series of thin diamond films doped with increasing levels of boron and monitored the samples with a technique called Raman spectroscopy. This technique uses pulses of laser light at specific wavelengths to measure the unique energy states in materials. Raman spectroscopy can be used for analysing the makeup of material or, as in this study, to watch how the energy states are affected by impurities.

Associate Professor Rongkun Zheng of the University of Sydney, a physicist not involved with the study, said: “Raman scattering probes the vibration and rotation of atoms or molecules in a sample, which is related to the superconductivity of the material.”

The team noticed a remarkable change in the energy states of the doped diamond. They concluded that their study provided a new understanding of how impurities effect the energy levels in diamonds and, perhaps more tenuously, that this could lead to a superconductive material that doesn’t have to be chilled to absolute zero.

The results, they believe, could inform the fabrication of materials for future applications such as high-performance electrical grids and high-speed transport.

Zheng, however, is less convinced. “The paper emphasised superconductivity but did not explore the effect on superconductivity. The significance and quality of this paper is very limited.”

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Andrew Stapleton is a scientist, science writer and podcaster based in Adelaide.
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