Effects of crystal field and momentum-based frustrated exchange interactions on multiorbital square skyrmion lattice

TL;DR

This study investigates how multiorbital effects and frustrated exchange interactions stabilize square skyrmion lattices in Ce-based magnets, revealing key mechanisms and diverse magnetic phases.

Contribution

It provides a comprehensive theoretical analysis of the microscopic mechanisms stabilizing square skyrmion lattices in multiorbital Ce-based magnets, highlighting the roles of interorbital coupling and anisotropy.

Findings

Cooperative interplay among interorbital coupling, frustrated exchange interactions, and anisotropy stabilizes the S-SkL.

Competition between easy-plane and easy-axis anisotropies enhances S-SkL stability.

Identifies various multi-Q states, including topologically nontrivial S-SkL' and magnetic bubble lattices.

Abstract

Motivated by recent theoretical predictions of a square-shaped skyrmion lattice (S-SkL) in centrosymmetric tetragonal Ce-based magnets [Yan Zha and Satoru Hayami, Phys. Rev. B 111, 165155 (2025)], we perform a comprehensive theoretical investigation into the role of multiorbital effects and momentum-based frustrated exchange interactions in stabilizing such topologically nontrivial magnetic textures. By employing self-consistent mean-field calculations over a broad range of model parameters, we demonstrate that the cooperative interplay among interorbital coupling, frustrated exchange interactions at higher-harmonic wave vectors, and crystal-field-induced anisotropy is crucial for the stabilization of the S-SkL. Furthermore, the competition between the easy-plane intraorbital anisotropy and the easy-axis interorbital anisotropy leads to a significant enhancement of the S-SkL stability region. We also identify a rich variety of multi-$Q$ states, including a topologically nontrivial S-SkL state with a slight breaking of fourfold rotational symmetry (S-SkL$'$), magnetic bubble lattices (MBLs), and double-$Q$ phases with a local/net scalar chirality. Our findings elucidate the microscopic mechanism responsible for the emergence of S-SkLs in prototypical Ce-based magnets and provide a route toward realizing skyrmion lattices in a broader class of $f$-electron materials beyond conventional Gd- and Eu-based systems lacking orbital angular momentum.