Intravalley spin-polarized superconductivity in rhombohedral tetralayer graphene
Yang-Zhi Chou, Jihang Zhu, S. Das Sarma
Abstract
We study the intravalley spin-polarized superconductivity in rhombohedral tetralayer graphene, which has been discovered experimentally in Han et al. [arXiv:2408.15233]. We construct a minimal model for the intravalley spin-polarized superconductivity, assuming a simplified anisotropic interaction that depends only on the angle between the incoming and outgoing momenta. Despite the absence of Fermi surface nesting, we show that superconductivity can emerge near the Van Hove singularity with the maximal ${T}_{c}$ near a bifurcation point of the peaks in the density of states. We identify the $p+ip$, $h+ih$, and the nodal $f$-wave pairings as the possible states, which are all pair density wave orders due to the intravalley nature. Furthermore, these pair density wave orders require a finite attractive threshold for superconductivity, resulting in a narrow stripe shape of superconducting region, consistent with experimental findings. We point out that the Kohn-Luttinger mechanism is a plausible explanation with a dominant $p+ip$ pairing. The possibility of realizing intravalley spin-polarized superconductivity in other rhombohedral graphene systems is also discussed.