An international research collaboration involving the University of Jyväskylä in Finland has achieved significant progress in superconductivity control technology, successfully developing an innovative method for completely suppressing superconductivity in both superconducting and ferromagnetic structures. This research, published in the prestigious journal Nature Communications, provides key technical support for the development of non-volatile superconducting random access memory, potentially enabling more energy-efficient solutions for future information and communications technologies. Building on theoretical predictions from over half a century ago, the research team experimentally demonstrated for the first time a de Gennes superconducting switch, in which superconductivity can be completely suppressed and restored.
Operating Principle and Theoretical Basis of Superconducting Switches
Superconductivity refers to a quantum state in which the electrical resistance of certain materials completely vanishes at a specific critical temperature. The superconducting switch engineering mechanism allows for precise control of the superconducting state through external control, similar to the switching device that switches current on and off in conventional circuits. The theoretical basis for the current research can be traced back to a theoretical model proposed in 1966 by the renowned physicist Pierre-Gilles de Gennes, which predicted that the critical temperature of a superconductor could be manipulated by changing the magnetization direction of the ferromagnetic layer, thereby enabling controlled switching of the superconducting state.
Technical Challenges and Innovative Solutions
Alberto Hijano, a postdoctoral researcher at the University of Jyväskylä, explained, “Although existing structures have demonstrated a certain sensitivity of the superconducting critical temperature to the magnetization direction, the observed critical temperature variation has always been far below the theoretically predicted value.” To address this long-standing technical challenge, the research team innovatively selected europium sulfide (EuS) as the insulating ferromagnetic material and niobium (Nb) as the superconductor, and introduced an extremely thin gold layer at the interface to enhance the near-field exchange effect. This material combination and structural design ultimately achieved complete suppression of superconductivity and controllable switching, achieving the perfect switching effect predicted by theory.
Application Prospects and Technical Advantages
This technological breakthrough lays a solid foundation for the practical application of superconducting memory. Hijano added, “Absolute superconducting switching will greatly promote the development of non-volatile superconducting random access memory. Compared with traditional thermal switches, the magnetically controlled switching mechanism can eliminate the continuous heat load, providing a new technical direction for the development of low-energy electronic devices.” The research was carried out in collaboration between the University of Cambridge, the University of the Basque Country, and the University of Jyväskylä. Its results are expected to significantly promote the practical application of superconducting technology in the field of energy-saving computing and bring the latest revolutionary changes to the next generation of information processing technology.
