2026-06-17 東京大学
原子スケールの電流の渦がつくる局所磁場
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-06-17-001
- https://www.nature.com/articles/s41567-026-03339-8
カゴメ金属における仮想電荷密度波の微視的特徴 Microscopic signatures of an imaginary charge density wave in a kagome metal
S. Suetsugu,F. Hori,M. Shibata,S. Kitagawa,K. Ishida,T. Asaba,S. Nakazawa,Q. Li,H. -H. Wen,T. Shibauchi,H. Kontani & Y. Matsuda
Nature Physics Published:17 June 2026
DOI:https://doi.org/10.1038/s41567-026-03339-8
Abstract
Loop current order has long been proposed as an unconventional electronic state arising from spontaneous symmetry breaking through the formation of microscopic electric current loops. The microscopic origin of these currents stems from imaginary hopping terms, conceptualized as an imaginary charge density wave. Despite extensive investigations, particularly in the context of the pseudogap state in high-temperature cuprate superconductors, its existence remains highly controversial. Here we demonstrate site-selective spectroscopic signatures of a pure imaginary charge density wave in the kagome non-magnetic metal CsV3Sb5. Nuclear quadrupole resonance spectra reveal anomalous broadening around a characteristic temperature of 120 K, which coincides with the nematic transition well above the real charge density wave order. In a magnetic field, the spectra exhibit antisymmetric lineshapes, demonstrating that this broadening purely originates from magnetic effects rather than from electric quadrupolar effects associated with charge order fluctuations. The observed lineshapes are quantitatively consistent with local fields induced by loop currents, indicating spontaneous time-reversal symmetry breaking. This microscopic evidence of a pure imaginary charge density wave suggests a distinct form of quantum order and extends our understanding of exotic electronic states in quantum materials.
