标题： 超导CeCoIn5中未凝聚的朗道费米面的量子振荡和拓扑变化 显示英文标题

标题： Quantum oscillation and topology change of the uncondensed Landau Fermi surface in superconducting CeCoIn5

摘要： 金属通常具有多个费米面片，当它们进入超导态时，这些片上的某些电子可能保持未凝聚，或者它们的超导对可能被磁场迅速破坏。 在超导态中检测未凝聚的电子提供了关于底层电子结构的关键信息；然而，这项任务仍然是一个重大的实验挑战。 在这里，我们展示了在重费米子超导体CeCoIn5中未凝聚电子的量子振荡，这是通过在四角形a-b平面内旋转磁场的热导率测量观察到的。 我们在热导率中检测到了一种精细结构，其特征是在旋转磁场中出现多个小的共振（振荡）。 值得注意的是，在9.7 T以上的磁场下，自旋密度波（SDW）序出现并与超导性共存时，这些共振的相位发生了高达{\pi }的变化。 这种相位变化可以通过未凝聚费米面的贝里相位的变化自然解释，这种变化是由SDW序开始时的费米面重构驱动的。 我们的工作明确证明了CeCoIn5超导态中存在未凝聚的电子，从而解决了关于这一问题的一个长期争论。 显示英文摘要

摘要： Metals typically have multiple Fermi surface sheets, and when they enter the superconducting state, some electrons on these sheets may remain uncondensed, or their superconducting pairs can be rapidly destroyed by a magnetic field. Detecting uncondensed electrons within the superconducting state provides key information about the underlying electronic structure; however, this task remains a significant experimental challenge. Here we demonstrate quantum oscillations from the uncondensed electrons in the heavy-fermion superconductor CeCoIn5, observed through thermal conductivity measurements with a magnetic field rotating within the tetragonal a-b plane. We detect a fine structure in thermal conductivity, characterized by multiple small resonances (oscillations) in a rotating magnetic field. Remarkably, the phase of these resonances shifted by as much as {\pi} for a field above 9.7 T where spin-density wave (SDW) order emerges and coexists with superconductivity. This phase shift is naturally explained by a change in the Berry phase of the uncondensed Fermi surface, driven by the Fermi surface reconstruction associated with the onset of SDW order. Our work unambiguously shows the existence of uncondensed electrons in the superconducting state of CeCoIn5, thus resolving a longstanding debate on this issue.