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China’s controls, to take effect from August 1, will apply to eight gallium-related products: gallium antimonide, gallium arsenide, gallium metal, gallium nitride, gallium oxide, gallium phosphide, gallium selenide and indium gallium arsenide.

Thanks to the unusual electronic properties of the indium antimonide, the researchers can control the flow of electrons across the bridge using a perpendicular magnetic field.

For one thing, indium antimonide, the semiconductor crucial to the circuits, doesn’t lend itself well to manufacturing processes used to make modern electronics, according to Junichi Murota, a researcher working with nanoelectronics at Tohoku University in Japan.

In his group's set-up, indium antimonide nanowires are connected to a circuit with a gold contact at one end and a slice of superconductor at the other, and then exposed to a moderately strong magnetic field.

When passed into silver nitrate solution it gives a black precipitate of silver antimonide, SbAg3.