近日，德国马克斯·普朗克固体化学物理研究所的C. W. Hicks&A. P. Mackenzie与德国卡尔斯鲁厄理工学院的J. Schmalian等人合作取得一项新进展。经过不懈努力，他们揭示了Sr₂RuO₄中Lifshitz跃迁时的巨型晶格软化现象。相关研究成果已于2023年10月27日在国际权威学术期刊《科学》上发表。

该研究团队通过测量应力-应变关系，并利用基于压电原理的单轴压力电池对超纯净金属钌酸锶进行精确调谐，揭示了二维费米表面在Lifshitz跃迁过程中杨氏模量的显著软化现象。研究结果表明，这种软化效应确实完全由相关能带的传导电子所驱动。

据悉，固体中电子自由度和结构自由度之间的相互作用是一个研究热点。60多年前，Lifshitz提出了一种违反直觉的可能性：在拓扑费米表面跃迁中，由传导电子驱动的晶格软化。然而，他预测的效应非常微小，至今尚未有令人信服的实验观测结果。

附：英文原文

Title: Giant lattice softening at a Lifshitz transition in Sr₂RuO₄

Author: H. M. L. Noad, K. Ishida, Y.-S. Li, E. Gati, V. Stangier, N. Kikugawa, D. A. Sokolov, M. Nicklas, B. Kim, I. I. Mazin, M. Garst, J. Schmalian, A. P. Mackenzie, C. W. Hicks

Issue&Volume: 2023-10-27

Abstract: The interplay of electronic and structural degrees of freedom in solids is a topic of intense research. More than 60 years ago, Lifshitz discussed a counterintuitive possibility: lattice softening driven by conduction electrons at topological Fermi surface transitions. The effect that he predicted, however, was small and has not been convincingly observed. Using a piezo-based uniaxial pressure cell to tune the ultraclean metal strontium ruthenate while measuring the stress-strain relationship, we reveal a huge softening of the Young’s modulus at a Lifshitz transition of a two-dimensional Fermi surface and show that it is indeed driven entirely by the conduction electrons of the relevant energy band.

DOI: adf3348

Source: https://www.science.org/doi/10.1126/science.adf3348