Oriented Triplet $p$-Wave Pairing from Fermi surface Anisotropy and Nonlocal Attraction

TL;DR

This study uses quantum Monte Carlo simulations to explore how Fermi surface anisotropy and nonlocal attraction induce oriented triplet p-wave pairing in a two-dimensional Hubbard model, revealing new pairing mechanisms.

Contribution

It demonstrates how nearest-neighbor attraction and hopping anisotropy cooperate to produce oriented triplet p-wave pairing, a novel insight into pairing mechanisms in correlated systems.

Findings

Identification of an oriented triplet p-wave pairing phase.

Hopping anisotropy suppresses s-wave coherence.

Nearest-neighbor attraction activates odd-parity pairing.

Abstract

Using constrained-path quantum Monte Carlo, we map the ground-state phase diagram versus the nearest-neighbor (NN) attraction $V$ and spin-dependent hopping anisotropy $\alpha$ for the two-dimensional attractive $t$--$U$--$V$ Hubbard model at filling $n\simeq0.85$. We identify an onsite $s$-wave superfluid, a Cooper pair Bose metal with an uncondensed Bose surface, and an oriented equal-spin triplet $p$-wave pairing phase. The NN attraction activates the odd-parity channel, while hopping anisotropy suppresses the competing $s$-wave coherence and selects a $p_x/p_y$ polar axis, and thus lowers the critical $|V_c|$ for the onset of triplet-dominant $p$-wave pairing. A channel-resolved Landau analysis provides a criterion for the Landau $p$-wave scale $V_c^{\mathrm L}(\alpha)$, consistent with the observed anisotropy dependence of $|V_c|$. Our results establish how NN interaction and Fermi surface anisotropy cooperate to generate the oriented triplet $p$-wave pairing, and suggest that cold-atom and altermagnetic platforms could potentially realize this mechanism.