发表机构
Centre for Theoretical and Computational Physics, College of Physics, Qingdao University; Centre for Quantum Technology Theory, Swinburne University of Technology（青岛大学物理学院理论计算物理中心; 斯威本科技大学量子技术理论中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究交变磁超导体中Bogoliubov费米面对集体模式的影响，发现其导致高度各向异性的朗道阻尼和隙内Higgs结构，并确立自旋响应为灵敏探针。
AI 中文摘要
我们研究了具有d波自旋劈裂能带的电荷中性交变磁超导体中的集体模式，重点关注涌现的Bogoliubov费米面的影响。在无磁场情况下，BCS态支持继承底层d波对称性的集体模式，导致显著的动量空间各向异性。时间反演对称性的破缺进一步将这些模式与自旋密度涨落耦合，使其特征能够出现在自旋动力学结构因子中。施加磁场后，Bogoliubov费米面涌现，并通过无能隙的粒子-空穴激发和强各向异性的朗道阻尼定性重塑集体模式动力学。阻尼在动量空间对角线上最强，可在小动量处抑制低能声子模式。值得注意的是，被抑制的声子伴随着Higgs模式中隙内结构的出现以及相关的自旋响应的显著增强。这些结果确立了Bogoliubov费米面作为产生高度各向异性集体模式动力学的机制，并确定自旋响应为交变磁超导体中隙内Higgs激发的灵敏探针。
英文摘要
We investigate collective modes in charge-neutral altermagnetic superconductors with $d$-wave spin-split bands, focusing on the impact of emergent Bogoliubov Fermi surfaces. In the absence of a magnetic field, the BCS state supports collective modes that inherit the underlying $d$-wave symmetry, resulting in pronounced momentum-space anisotropy. The broken time-reversal symmetry further couples these modes to spin-density fluctuations, allowing their signatures to emerge in the spin dynamical structure factor. Upon applying a magnetic field, Bogoliubov Fermi surfaces emerge and qualitatively reshape the collective-mode dynamics through gapless particle-hole excitations and strongly anisotropic Landau damping. The damping is strongest along the momentum-space diagonal, where it can suppress the low-energy phonon mode at small momenta. Remarkably, the suppressed phonon is accompanied by the emergence of an in-gap structure in the Higgs mode and an associated pronounced enhancement of the spin response. These results establish Bogoliubov Fermi surfaces as a mechanism for generating highly anisotropic collective-mode dynamics and identify spin response as a sensitive probe of in-gap Higgs excitations in altermagnetic superconductors.
Comments10 pages; 8 figures
