Magnetic anisotropies and skyrmion lattice related to magnetic quadrupole interactions of the RKKY mechanism in the frustrated spin-trimer system <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>Gd</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> <mml:msub> <mml:mtext>Ru</mml:mtext> <mml:mn>4</mml:mn> </mml:msub> <mml:msub> <mml:mtext>Al</mml:mtext> <mml:mn>12</mml:mn> </mml:msub> </mml:mrow> </mml:math> with a breathing kagome structure
Shintaro Nakamura
Abstract
The origin of the magnetic quadrupole (MQ) interactions in ${\mathrm{Gd}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$, which is known as a frustrated spin system and as a host material for skyrmion with a centrosymmetric crystal structure, are discussed. The MQ interactions between ferromagnetic (FM) spin trimers with imperfect FM directivity are deduced from a 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 the 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 the SkL which appears at finite temperatures.