近日，美国国家高磁场实验室Mun K. Chan团队研究了铜超导体中Yamaji效应的观察。相关论文于2025年9月16日发表在《自然—物理学》杂志上。

高温超导铜酸盐的赝隙态，以其费米表面在超导转变温度以上的部分间隙而闻名，被认为是理解普朗克弛豫和量子临界起源的关键。然而，赝隙状态下费米表面的性质仍然是一个基本的开放性问题。

研究组报道了在临界温度以上的铜酸盐HgBa2CuO4+δ的角相关磁电阻率测量中观察到的Yamaji效应，该效应在外加磁场特定角度处的c轴电阻率出现峰值。Yamaji峰的观测证明在赝隙相的正常状态下存在小的费米表面口袋。估计每个口袋只占布里渊区面积的1.3%，考虑到缺乏长程破缺平移对称性，这是不可能的。

附：英文原文

Title: Observation of the Yamaji effect in a cuprate superconductor

Author: Chan, Mun K., Schreiber, Katherine A., Ayala-Valenzuela, Oscar E., Bauer, Eric D., Shekhter, Arkady, Harrison, Neil

Issue&Volume: 2025-09-16

Abstract: The pseudogap state of high-temperature superconducting cuprates, known for its partial gapping of the Fermi surface above the superconducting transition temperature, is believed to hold the key to understanding the origin of Planckian relaxation and quantum criticality. However, the nature of the Fermi surface in the pseudogap state has remained a fundamental open question. Here we report the observation of the Yamaji effect, which appears as a peak in the c-axis resistivity at a specific angle of the applied magnetic field, in angle-dependent magnetoresistivity measurements above the critical temperature in the cuprate HgBa2CuO4+δ. The observation of the Yamaji peak is evidence for small Fermi-surface pockets in the normal state of the pseudogap phase. The small size of the pockets, each estimated to occupy only 1.3% of the Brillouin zone area, is not expected given the absence of long-range broken translational symmetry.

DOI: 10.1038/s41567-025-03032-2

Source: https://www.nature.com/articles/s41567-025-03032-2