DATE2025.11.07 #Press Releases
Discovery of a Unique Electronic State, “Nodal Metal,” in Cuprate High-Temperature Superconductors
- Shedding light on how the trilayer structure realizes high superconductivity -
Summary
An international research team has discovered a special electronic state called a “nodal metal” in a trilayer cuprate high-temperature superconductor containing three CuO₂ planes. This is the first observation of such a state in the world, detected at temperatures above the superconducting transition temperature (Tc).
The discovery was made by Associate Professor Shinichiro Ideta and Technical Staff Masashi Arita of the Hiroshima Synchrotron Radiation Center, Professor Teppei Yoshida of Kyoto University, Professors Emeritus Atsushi Fujimori and Shin-ichi Uchida, and Assistant Professor Takenori Fujii of the Cryogenic Research Center, The University of Tokyo, together with collaborators from Hirosaki University, the Institute for Molecular Science / SOKENDAI, AIST, Tohoku University, National Tsing Hua University (Taiwan), and Stanford University (USA).
Using high-resolution angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation, the team revealed how the nodal-metal state depends on the carrier concentration. They found that even in CuO₂ planes with very low carrier density, superconducting electrons exist at temperatures far above Tc. In addition, the superconducting energy gap was significantly larger than in conventional high-temperature superconductors. This suggests that superconductivity is stabilized by a “proximity effect” between the two outer and one inner CuO₂ planes.
By clarifying why trilayer cuprates exhibit the highest Tc values, this research provides important insight into the origin of high-temperature superconductivity and offers valuable guidelines for designing new materials that could one day achieve room-temperature superconductivity.
The study was published online in Nature Communications on October 27, 2025 (UK time).
This work was supported by JSPS KAKENHI (Grant Numbers: 20H01861, 22K03535, 23K20229, 24K06961, 25400349), the National Science and Technology Council and Ministry of Education of Taiwan, and the U.S. Department of Energy (DOE), as well as by joint research programs of the Hiroshima Synchrotron Radiation Center(Project Nos. 22AG006, 23BG011) and the Institute for Molecular Science (Project Nos. 29-549, 31-572, 31-861).
Figure：Crystal structure of a trilayer cuprate superconductor (three CuO₂ planes)
Links
Hiroshima University, Institute for Molecular Science, Kyoto University, Hirosaki University, University of Tokyo Low Temperature Science Center, Kyoto Institute for Advanced Science,Graduate University for Advanced Studies, SOKENDAI
Journals
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Journal name Title of paper Proximity-Induced Nodal Metal in an Extremely Underdoped CuO2 Plane in Triple-layer Cuprates