瑞士保罗谢勒研究所Rustem Khasanov团队研究了La3Ni2O7-δ中密度波跃迁的压力增强分裂。相关论文发表在2025年2月17日出版的《自然—物理学》杂志上。
在高温密度波态被抑制后，La3Ni2O7-δ在压力下的超导电性观测引起了人们的广泛关注。这种密度波序的性质尚不清楚。
研究组分析了静水压力作用下La3Ni2O7-δ零压力相的磁响应，发现零压力下的表观单密度波转变分为两个。通过对其介子自旋和弛豫实验与偶极子场数值分析的比较，揭示了该磁性结构与Ni磁矩的条形排列的相容性，其特征是在环境压力下磁矩线和非磁条的交替排列。施加压力时，磁有序温度升高，而未识别密度波转变温度下降。
该发现揭示了La3Ni2O7-δ体系基态特征是两个不同序的共存（一种是磁有序的自旋密度波，另一种是温度较低的有序态，很可能是电荷密度波），且两者之间的分离在压力作用下显著增强。
Title: Pressure-enhanced splitting of density wave transitions in La3Ni2O7–δ
Author: Khasanov, Rustem, Hicken, Thomas J., Gawryluk, Dariusz J., Sazgari, Vahid, Plokhikh, Igor, Sorel, Loc Pierre, Bartkowiak, Marek, Btzel, Steffen, Lechermann, Frank, Eremin, Ilya M., Luetkens, Hubertus, Guguchia, Zurab
Issue&Volume: 2025-02-17
Abstract: The observation of superconductivity in La3Ni2O7–δ under pressure, following the suppression of a high-temperature density wave state, has attracted considerable attention. The nature of this density wave order was not clearly identified. Here we probe the magnetic response of the zero-pressure phase of La3Ni2O7–δ as hydrostatic pressure is applied, and find that the apparent single density wave transition at zero applied pressure splits into two. The comparison of our muon-spin rotation and relaxation experiments with dipole-field numerical analysis reveals the magnetic structure’s compatibility with a stripe-type arrangement of Ni moments, characterized by alternating lines of magnetic moments and non-magnetic stripes at ambient pressure. When pressure is applied, the magnetic ordering temperature increases, whereas the unidentified density wave transition temperature falls. Our findings reveal that the ground state of the La3Ni2O7–δ system is characterized by the coexistence of two distinct orders—a magnetically ordered spin density wave and a lower-temperature ordering that is most probably a charge density wave—with a notable pressure-enhanced separation between them.
DOI: 10.1038/s41567-024-02754-z
Source: https://www.nature.com/articles/s41567-024-02754-z