Superconductivity is a special state of matter where electrical current can flow through a material with zero resistance, enabling perfect electronic transport efficiency. Power electromagnets use superconductors for technologies like magnetic resonance imaging, particle accelerators, fusion reactors, and levitating trains.
They’re also crucial for advancements in quantum computing. Unlike traditional semiconductors in electronics that generate heat due to resistance, superconductors operate at extremely low temperatures, making them impractical for everyday devices but valuable for large-scale industrial applications.
Scientists led by Jiun-Haw Chu, a University of Washington associate professor of physics and Clean Energy Institute researcher, and Philip Ryan, a physicist at the U.S. Department of Energy’s Argonne National Laboratory, examined an unusual superconducting material with exceptional tunability.
This new material is uniquely sensitive to outside stimuli, enabling the superconducting properties to be enhanced or suppressed at will. This discovery could help new opportunities for switchable, energy-efficient superconducting circuits.
This crystal comprises superconducting iron, cobalt, and arsenic atoms layered between flat sheets of ferromagnetic europium atoms. According to Sanchez, it is uncommon to find ferromagnetism and superconductivity combined in nature because they are typically overpowering in one over the other.
The interaction between superconducting layers and magnetic fields from surrounding europium atoms can compromise superconductivity, leading to a finite electrical resistance. To delve into this interaction, Sanchez spent a year at the Advanced Photon Source, a leading X-ray light source. Collaborating with physicists, he developed a platform to comprehensively characterize complex materials, allowing microscopic exploration of the intricate details involved in this phenomenon.
Sanchez and his team utilized X-ray techniques to demonstrate that applying a magnetic field to the crystal can align europium magnetic field lines parallel to the superconducting layers. This alignment eliminates their antagonistic effects, facilitating the emergence of a zero-resistance state. Through electrical measurements and X-ray scattering techniques, scientists verified their ability to control the material’s behavior in response to these conditions.
Ryan said, “The nature of independent parameters controlling superconductivity is quite fascinating, as one could map out a complete method of controlling this effect. This potential posits several fascinating ideas, including the ability to regulate field sensitivity for quantum devices.”
The research team discovered that applying stresses to the crystal yielded intriguing outcomes. They observed that superconductivity could be enhanced sufficiently to overcome magnetism, even without reorienting the magnetic field. Conversely, the material’s sensitivity to magnetism could be diminished because magnetic reorientation failed to induce the zero-resistance state. This added parameter provides the ability to control and tailor the material’s responsiveness 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,” explained Sanchez. “The vast majority of superconductors aren’t nearly as easily switchable.”
Journal Reference:
- Joshua Sanchez, Gilberto Fabbris, Yongseong Choi, et al. Strain-switchable field-induced superconductivity. Science Advances. DOI: 10.1126/sciadv.adj5200