Novel approach lets scientists draw superconducting patterns

Superconductivity has fascinated scientists for many years, since it offers the potential to revolutionize current technologies, but materials only become superconductors – allowing electrons to travel in them with no resistance – at very low temperatures.

Several current technologies, such as magnetic resonance imaging (MRI), take advantage of zero-resistance superconductivity. Future technologies, however, will harness the total synchrony of electronic behavior in superconductors – a property called the phase. There is currently a race to build the world's first quantum computer, which will use these phases to perform calculations. Conventional superconductors are very robust and hard to influence, and the challenge is to find new materials in which the superconducting state can be easily manipulated.

The Ecole Polytechnique Fédérale de Lausanne (EPFL)'s Laboratory of Quantum Materials (QMAT) in Switzerland, headed by Philip Moll, has been working on a specific group of unconventional superconductors known as heavy fermion materials. The QMAT scientists, as part of a broad international collaboration between EPFL, the Max Planck Institute for Chemical Physics of Solids in Germany, the Los Alamos National Laboratory and Cornell University, have now made a surprising discovery about one of these materials, CeIrIn₅.

CeIrIn₅ is a metal that superconducts at a very low temperature, only 0.4°C above absolute zero (around -273°C). The QMAT scientists, together with Katja Nowack from Cornell University, have now shown that this material can be produced with superconducting regions coexisting alongside regions in a normal metallic state. Better still, the scientists produced a model that allows researchers to design complex conducting patterns and, by varying the temperature, to distribute them within the material in a highly controlled way. They report this work in a paper in Science.

To achieve this feat, the scientists sliced very thin layers of CeIrIn₅ – only around a thousandth of a millimeter thick – and attached them to a sapphire substrate. When cooled, the CeIrIn₅ layer contracts significantly whereas the sapphire substrate contracts very little. The resulting interaction puts stress on the material, as if it were being pulled in all directions, thus slightly distorting the atomic bonds in the layer.

As the superconductivity in CeIrIn₅ is unusually sensitive to the material's exact atomic configuration, engineering a distortion pattern is all it takes to achieve a complex pattern of superconductivity. This new approach allows researchers to ‘draw’ superconducting circuitry on a single crystal bar, a step that paves the way for new quantum technologies.

This discovery represents a major step forward in controlling superconductivity in heavy fermion materials. But that's not the end of the story. Following on from this project, a postdoc researcher at EPFL has just begun exploring possible technological applications.

"We could, for example, change the regions of superconductivity by modifying the material's distortion using a microactuator," explains Moll. "The ability to isolate and connect superconducting regions on a chip could also create a kind of switch for future quantum technologies, a little like the transistors used in today's computing."

This story is adapted from material from EPFL, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.