New Dimension to High-Temperature Superconductivity

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Image - In this artistic rendering, a magnetic pulse (right) and X-ray laser light (left) converge on a superconductor material to study the behavior of its electrons. (SLAC National Accelerator Laboratory)

In this artistic rendering, a magnetic pulse (right) and X-ray laser light (left) converge on a high-temperature superconductor to study the behavior of its electrons. (SLAC National Accelerator Laboratory)

A team has combined powerful magnetic pulses with some of the brightest X-rays on the planet to discover a surprising 3D arrangement of a material’s electrons that appears closely linked to a mysterious phenomenon known as high-temperature superconductivity. It also resolves an apparent mismatch in data from previous experiments and charts a new course for fully mapping the behaviors of electrons in these exotic materials under different conditions.

“This was totally unexpected, and also very exciting…Nobody had seen this 3D picture before,” said Jun-Sik Lee, at SLAC. The dream is to push the operating temperature for superconductors to room temperature, he added, which could lead to advances in computing, electronics and power grid technologies besides MRI, CERN particle collider. A planned upgrade to the LCLS, known as LCLS-II, will include a superconducting particle accelerator.

The 3D effect in the LCLS experiment in superconducting YBCO (yttrium barium copper oxide), is a newly discovered type of “charge density wave.” This wave does not have the oscillating motion of a light wave or a sound wave; it describes a static, ordered arrangement of clumps of electrons in a superconducting material. Its coexistence with superconductivity is perplexing to researchers because it seems to conflict with the freely moving electron pairs that define superconductivity.

Image - This custom-made magnet was used in an experiment at SLAC's Linac Coherent Light Source X-ray laser to study an effect known as a charge density wave. (Courtesy Jun-Sik Lee)

This custom-made magnet was used in an experiment at SLAC’s Linac Coherent Light Source X-ray laser to study an effect known as a charge density wave. (Courtesy Jun-Sik Lee)

Those short but intense magnetic pulses suppressed the superconductivity of the YBCO samples and provided a clearer view of the charge density wave effects. They were immediately followed at precisely timed intervals by ultrabright LCLS X-ray laser pulses, which allowed scientists to measure the wave effects. But it is also clear that YBCO is incredibly complex, and a more complete map of all of its properties is required to reach any conclusions about what matters most to its superconductivity.

The experiment also adds weight to the growing evidence that charge density waves and superconductivity “can be thought of as two sides of the same coin,” he added. Follow-up experiments are needed to provide a detailed visualization of the 3-D effect, and to learn whether the effect is universal across all types of high-temperature superconductors. https://www6.slac.stanford.edu/news/2015-11-05-researchers-discover-new-dimension-high-temperature-superconductivity.aspx