Scientists Discover Groundbreaking Superconductor With On-Off Switches

Breakthrough in Superconductivity Research

Physicists at the University of Washington and the U.S. Department of Energy’s (DOE) Argonne National Laboratory have made a discovery that could help enable this more efficient future. Researchers have found a superconducting material that is uniquely sensitive to outside stimuli, enabling the superconducting properties to be enhanced or suppressed at will. This enables new opportunities for energy-efficient switchable superconducting circuits. The paper was published in Science Advances.

Superconductivity is a quantum mechanical phase of matter in which an electrical current can flow through a material with zero resistance. This leads to perfect electronic transport efficiency. Superconductors are used in the most powerful electromagnets for advanced technologies such as magnetic resonance imaging, particle accelerators, fusion reactors, and even levitating trains. Superconductors have also found uses in quantum computing.

Challenges and Innovations in Superconducting Technologies

Today’s electronics use semiconducting transistors to quickly switch electric currents on and off, creating the binary ones and zeroes used in information processing. As these currents must flow through materials with finite electrical resistance, some of the energy is wasted as heat. This is why your computer heats up over time. The low temperatures needed for superconductivity, usually more than 200 degrees Fahrenheit below freezing, makes those materials impractical for hand-held devices. However, they could conceivably be useful on an industrial scale.

The research team, led by Shua Sanchez of the University of Washington, examined an unusual superconducting material with exceptional tunability. This crystal is made of flat sheets of ferromagnetic europium atoms sandwiched between superconducting layers of iron, cobalt, and arsenic atoms. Finding ferromagnetism and superconductivity together in nature is extremely rare, according to Sanchez, as one phase usually overpowers the other.

Advanced Research Techniques and Findings

To understand the interaction of these phases, Sanchez spent a year as a resident at one of the nation’s leading X-ray light sources, the Advanced Photon Source (APS), a DOE Office of Science user facility at Argonne. While there he was supported by DOE’s Science Graduate Student Research program. Working with physicists at APS beamlines 4-ID and 6-ID, Sanchez developed a comprehensive characterization platform capable of probing the microscopic details of complex materials.

The team then applied stresses to the crystal with interesting results. They found the superconductivity could be either boosted enough to overcome the magnetism even without re-orienting the field or weakened enough that the magnetic reorientation could no longer produce the zero-resistance state. This additional parameter allows for the material’s sensitivity to magnetism to be controlled and customized.

“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.”