We present a theory for charge-4e superconductivity as a leading low-temperature instability with a nontrivial d-wave symmetry. We show that in several microscopic models for the pair-density-wave (PDW) state, when the PDW wave vectors connect special parts of the Fermi surface, the predominant interaction is in the bosonic pairing channel mediated by exchanging low-energy fermions. This bosonic pairing interaction is repulsive in the s-wave channel but attractive in the d-wave one, leading to a d-wave charge-4e superconductor. By analyzing the Ginzburg-Landau free energy including higher-order fluctuation effects of PDW, we find that the charge-4e superconductivity emerges as a vestigial order of PDW, and sets in via a first-order transition. Both the gap amplitude and the transition temperature decay monotonically with increasing superfluid stiffness of the PDW order. Our work provides a microscopic mechanism of higher-charge condensates with unconventional ordering symmetry in strongly-correlated materials.

我们提出了一种电荷 4 e超导理论，该理论是一种具有非平凡d波对称性的主要低温不稳定性。我们表明，在对密度波（PDW）态的几个微观模型中，当PDW波矢量连接费米表面的特殊部分时，主要的相互作用发生在通过交换低能费米子介导的玻色子配对通道中。这种玻色子配对相互作用在s波通道中是排斥的，但在d波通道中是吸引的，从而形成d波电荷 4 e超导体。通过分析包括PDW高阶涨落效应在内的Ginzburg-Landau自由能，我们发现电荷4e超导性以PDW的残余阶的形式出现，并通过一阶跃迁开始。随着 PDW 阶超流体刚度的增加，间隙幅度和转变温度均单调衰减。我们的工作提供了强相关材料中具有非常规有序对称性的高电荷凝聚态的微观机制。