Meng Yanghao, Yang Yi, Sun Hualei, Zhang Sasa, Luo Jianlin, Chen Liucheng, Ma Xiaoli, Wang Meng, Hong Fang, Wang Xinbo, Yu Xiaohui
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2024 Nov 29;15(1):10408. doi: 10.1038/s41467-024-54518-1.
Density wave (DW) order is believed to be correlated with superconductivity in the recently discovered high-temperature superconductor LaNiO. However, experimental investigations of its evolution under high pressure are still lacking. Here, we explore the quasiparticle dynamics in bilayer nickelate LaNiO single crystals using ultrafast optical pump-probe spectroscopy under high pressures up to 34.2 GPa. At ambient pressure, the temperature-dependent relaxation dynamics demonstrate a phonon bottleneck effect due to the opening of an energy gap around 151 K. The energy scale of the DW-like gap is determined to be 66 meV by the Rothwarf-Taylor model. Combined with recent experiential results, we propose that this DW-like transition at ambient pressure and low temperature is spin density wave (SDW). With increasing pressure, this SDW order is significantly suppressed up to 13.3 GPa before it completely disappears around 26 GPa. Remarkably, at pressures above 29.4 GPa, we observe the emergence of another DW-like order with a transition temperature of approximately 135 K, which is probably related to the predicted charge density wave (CDW) order. Our study provides the experimental evidences of the evolution of the DW-like gap under high pressure, offering critical insights into the correlation between DW order and superconductivity in LaNiO.
密度波（DW）序被认为与最近发现的高温超导体LaNiO中的超导性相关。然而，目前仍缺乏对其在高压下演变的实验研究。在此，我们利用超快光泵浦-探测光谱技术，在高达34.2吉帕的高压下，对双层镍酸盐LaNiO单晶中的准粒子动力学进行了研究。在常压下，与温度相关的弛豫动力学表明，由于在151K左右出现能隙，存在声子瓶颈效应。通过Rothwarf-Taylor模型确定，类DW能隙的能量尺度为66毫电子伏特。结合最近的实验结果，我们提出，在常压和低温下的这种类DW转变是自旋密度波（SDW）。随着压力增加，这种SDW序在高达13.3吉帕时被显著抑制，在26吉帕左右完全消失。值得注意的是，在高于29.4吉帕的压力下，我们观察到出现了另一种类DW序，其转变温度约为135K，这可能与预测的电荷密度波（CDW）序有关。我们的研究提供了高压下类DW能隙演变的实验证据，为LaNiO中DW序与超导性之间的相关性提供了关键见解。
