Imaging the Meissner effect in hydride superconductors using quantum sensors

• Published in: Nature (London) Vol. 627; no. 8002; pp. 73 - 79
• Main Authors: Bhattacharyya, P., Chen, W., Huang, X., Chatterjee, S., Huang, B., Kobrin, B., Lyu, Y., Smart, T. J., Block, M., Wang, E., Wang, Z., Wu, W., Hsieh, S., Ma, H., Mandyam, S., Chen, B., Davis, E., Geballe, Z. M., Zu, C., Struzhkin, V., Jeanloz, R., Moore, J. E., Cui, T., Galli, G., Halperin, B. I., Laumann, C. R., Yao, N. Y.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.03.2024; Nature Publishing Group
• Subjects: 639/301; 639/301/930/2735; 639/766; 639/766/119/1003; 639/766/483/1255; Anvils; Closed loops; Color centers; Cooling; Diamagnetism; Diamond anvil cells; Electrons; Geometry; High temperature; High temperature superconductors; Humanities and Social Sciences; Hydrides; Magnetic fields; Magnetic measurement; MATERIALS SCIENCE; Measurement techniques; multidisciplinary; Nitrogen; Phase transitions; Quantum sensors; Science; Science (multidisciplinary); Spatial discrimination; Spatial resolution; Spectrum analysis; Superconductivity
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-024-07026-7

By directly altering microscopic interactions, pressure provides a powerful tuning knob for the exploration of condensed phases and geophysical phenomena 1 . The megabar regime represents an interesting frontier, in which recent discoveries include high-temperature superconductors, as well as structural and valence phase transitions 2 – 6 . However, at such high pressures, many conventional measurement techniques fail. Here we demonstrate the ability to perform local magnetometry inside a diamond anvil cell with sub-micron spatial resolution at megabar pressures. Our approach uses a shallow layer of nitrogen-vacancy colour centres implanted directly within the anvil 7 – 9 ; crucially, we choose a crystal cut compatible with the intrinsic symmetries of the nitrogen-vacancy centre to enable functionality at megabar pressures. We apply our technique to characterize a recently discovered hydride superconductor, CeH 9 (ref.  10 ). By performing simultaneous magnetometry and electrical transport measurements, we observe the dual signatures of superconductivity: diamagnetism characteristic of the Meissner effect and a sharp drop of the resistance to near zero. By locally mapping both the diamagnetic response and flux trapping, we directly image the geometry of superconducting regions, showing marked inhomogeneities at the micron scale. Our work brings quantum sensing to the megabar frontier and enables the closed-loop optimization of superhydride materials synthesis. In order to explore superconductivity in hydride materials, local magnetometry inside a diamond anvil cell is performed with sub-micron spatial resolution at megabar pressures using nitrogen-vacancy colour centres.