近日，美国普林斯顿大学的B. Andrei Bernevig及其研究团队取得一项新进展。经过不懈努力，他们对电子-声子耦合的非平凡量子几何和强度进行了研究。相关研究成果已于2024年5月27日在国际知名学术期刊《自然—物理学》上发表。

该研究团队设计了一个理论，将电子带的量子几何特性与电子-声子耦合相结合，从而揭示了富比尼–施图迪度量或其轨道选择性版本，对无量纲电子-声子耦合常数具有显著影响。他们将该理论应用于石墨烯和MgB₂这两种材料，发现量子几何贡献在石墨烯中约占电子-声子耦合总常数的50%，而在MgB₂中更是高达90%。

进一步的研究表明，这两个系统中的量子几何贡献还受到拓扑特性的界定。这一发现具有重要意义，它表明非平凡的电子带几何或拓扑结构，可能有助于在相对较高的临界温度下实现超导性。

据悉，电子-声子耦合对于物质的各种相，特别是超导和密度波的存在是至关重要的。

附：英文原文

Title: Non-trivial quantum geometry and the strength of electron–phonon coupling

Author: Yu, Jiabin, Ciccarino, Christopher J., Bianco, Raffaello, Errea, Ion, Narang, Prineha, Bernevig, B. Andrei

Issue&Volume: 2024-05-27

Abstract: Electron–phonon coupling is crucial for the existence of various phases of matter, in particular superconductivity and density waves. Here, we devise a theory that incorporates the quantum geometry of the electron bands into the electron–phonon coupling, demonstrating the crucial contributions of the Fubini–Study metric or its orbital selective version to the dimensionless electron–phonon coupling constant. We apply the theory to two materials, that is, graphene and MgB₂, where the geometric contributions account for approximately 50% and 90% of the total electron–phonon coupling constant, respectively. The quantum geometric contributions in the two systems are further bounded from below by topological contributions. Our results suggest that the non-trivial electron band geometry or topology might favour superconductivity with a relatively high critical temperature.

DOI: 10.1038/s41567-024-02486-0

Source: https://www.nature.com/articles/s41567-024-02486-0