Magnetic Anisotropies and Skyrmion Lattice Related to Magnetic Quadrupole Interactions of the RKKY Mechanism in Frustrated Spin-Trimer System Gd$_{3}$Ru$_{4}$Al$_{12}$ with a Breathing Kagome Structure

TL;DR

This paper investigates how magnetic quadrupole interactions, derived from RKKY mechanisms in a frustrated spin-trimer system, influence magnetic anisotropies and stabilize skyrmion lattices in Gd$_{3}$Ru$_{4}$Al$_{12}$.

Contribution

It introduces a Hamiltonian incorporating MQ and dipole interactions, revealing their role in magnetic properties and skyrmion stabilization in a frustrated kagome system.

Findings

MQ interactions contribute to skyrmion lattice stability.

Magnetic anisotropies are influenced by MQ degrees of freedom.

The proposed Hamiltonian explains phase transitions in the system.

Abstract

The origin of the magnetic quadrupole (MQ) interactions in Gd$_{3}$Ru$_{4}$Al$_{12}$ which is known as a frustrated spin system and as a host material of skyrmion with a sentrosymmetric crystal structure are discussed. The MQ interactions between ferromagnetic (FM) spin trimers with imperfect FM directivity are deduced from synthesis of dipole Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. The Hamiltonian which includes both the MQ interactions and dipole interactions is proposed, and magnetic anisotropies, magnetic phase transitions and contribution of the MQ interactions to stabilize the skyrmion lattice (SkL) are discussed based on this Hamiltonian. Degrees of MQ freedom carried by the trimers contribute to stabilizing SkL which appears at finite temperatures.