Construction of an Innovative Superconductor Featuring Controllable Switches

A group of physicists has identified a novel superconducting substance with exceptional responsiveness to exterior stimuli, a development that holds the potential for significant progress in energy-efficient computing and quantum technology. The team achieved this using advanced research techniques, permitting unmatched influence over superconducting attributes, possibly transforming large-scale industrial applications.

The team leveraged the Advanced Photon Source to confirm the unique features of this material, potentially laying the groundwork for more efficient large-scale computing.

The industry's growing computing needs drive an increase in the dimension and energy requirements of the hardware necessary to meet these demands. Superconducting substances could be a potential solution to alleviate these energy requirements significantly. For instance, cooling a large data center packed with constantly operating servers to almost absolute zero could enable large-scale computation with incredible energy efficiency.

Physicists from the University of Washington and the U.S. Department of Energy’s (DOE) Argonne National Laboratory have made a discovery that could facilitate this increasingly efficient future. They identified a superconducting material with a unique sensitivity to external stimuli which allows superconducting properties to be heightened or impeded at will. This discovery opens up new possibilities for energy-efficient, switchable superconducting circuits. The research findings were published in Science Advances.

Superconductivity is a quantum mechanical state wherein an electric current can pass through a material with zero resistance, resulting in perfect electronic transport efficiency. Superconductors are utilized in powerful electromagnets for advanced technologies such as magnetic resonance imaging, particle accelerators, fusion reactors, and levitating trains, as well as in quantum computing.

Current electronics employ semiconducting transistors for quickly switching electric currents on and off, forming the binary ones and zeroes used in information processing. Due to the current flowing through materials with finite electrical resistance, some energy dissipates as heat, causing your computer to heat up over time. The low temperatures required for superconductivity, typically over 200 degrees Fahrenheit below freezing, render these materials unfeasible for portable devices. However, they could potentially be useful on an industrial scale.

Under the leadership of Shua Sanchez from the University of Washington, the research group studied an unusual superconducting material with extraordinary tunability. This crystal is composed of a flat sheet of ferromagnetic europium atoms encased between superconducting layers of iron, cobalt, and arsenic atoms. The presence of both ferromagnetism and superconductivity in nature is remarkably uncommon, Sanchez noted, owing to one phase usually dominating the other.

“The superconducting layers are in a somewhat uncomfortable situation, infiltrated by the magnetic fields from the surrounding europium atoms,” Sanchez stated, "This impairs the superconductivity, leading to a finite electrical resistance."

Sanchez spent a year at one of the country's top X-ray light sources, the Advanced Photon Source (APS), a DOE Office of Science user facility at Argonne. During his residency, supported by the DOE's Science Graduate Student Research Program, Sanchez collaborated with APS beamlines physicists to develop an in-depth characterization platform capable of probing the microscopic details of complex materials.

Sanchez and his team utilized an array of X-ray techniques to establish that exerting a magnetic field to the crystal can align the europium magnetic field lines with the superconducting layers, removing their harmful effects and creating a zero-resistance state. Using electrical measurements and X-ray scattering methods, the scientists ascertained that they could control the material's behavior.

According to Philip Ryan of Argonne, a co-author of the paper, "The fascinating nature of the independent parameters controlling superconductivity allows for a comprehensive method of managing this effect." He continues, "This potential suggests several exciting possibilities, including the ability to regulate field sensitivity for quantum devices."

The group proceeded to apply different stress levels to the crystal, discovering that superconductivity could be either enhanced enough to triumph over the magnetism without the need for field re-orientation or weakened enough that magnetic re-orientation no longer resulted in the zero-resistance state. This additional parameter enables the regulation and customization of the material’s sensitivity to magnetism.

“This material is exciting because you have a close competition between multiple phases, and by applying a small stress or magnetic field, you can boost one phase over the other to turn the superconductivity on and off,” Sanchez said. ​“The vast majority of superconductors aren’t nearly as easily switchable.”