Cooper Pair Induced Frustration and Nematicity of Two-Dimensional Magnetic Adatom Lattices

TL;DR

This paper explores how Cooper pairs can induce magnetic frustration in 2D magnetic adatom lattices on superconductors, leading to hidden order states and nematicity, with a phase diagram revealing vestigial nematic order.

Contribution

It introduces a novel mechanism using Cooper pairs to induce frustration and nematicity in 2D magnetic adatom systems, supported by a new effective bond theory.

Findings

Identification of hidden order states breaking lattice symmetry

Broad regions of long-range vestigial nematic order in the phase diagram

Demonstration of competition between electron correlations and RKKY coupling

Abstract

We propose utilizing the Cooper pair to induce magnetic frustration in systems of two-dimensional (2D) magnetic adatom lattices on s-wave superconducting surfaces. The competition between singlet electron correlations and the RKKY coupling is shown to lead to a variety of hidden order states that break the point-group symmetry of the 2D adatom lattice at finite temperature. The phase diagram is constructed using a newly developed effective bond theory [M. Schecter et al., Phys. Rev. Lett. 119, 157202 (2017)], and exhibits broad regions of long-range vestigial nematic order.