Because superconductors are generally very sensitive to magnetic fields, developing superconductors that operate stably under strong magnetic fields is a crucial challenge for the advancement of superconducting wires and quantum devices. A new type of superconductivity called "spin triplet" has been discovered in the uranium-containing superconductor UTe₂ (uranium-tellurium compound). In addition, a phenomenon—the strengthening of superconductivity under strong magnetic fields—that overturns conventional wisdom has been confirmed.
 In this study, we used nuclear magnetic resonance (NMR) spectroscopy to investigate the mechanism of the enhancement of superconductivity under strong magnetic fields. Our experiment revealed that upon applying a strong magnetic field, magnetic fluctuations within materials increase, thereby strengthening bonding between electron pairs (Cooper pairs) responsible for superconductivity (Fig. 1). Thus, a superconducting state resilient to magnetic fields is realized.
 This discovery indicates that in spin-triplet superconductors, magnetism and superconductivity are deeply interconnected. Furthermore, this result suggests that by applying this principle, superconductors with strong magnetic-field resistance can be developed using compounds that do not contain uranium. Such superconductors are extremely important for developing high-performance superconducting wires and quantum devices; therefore, they hold remarkable potential for expanding the applications of superconducting technology.

This work was supported by JSPS KAKENHI Grant Number JP20KK0061.