Orbital Magnetic Moment of Magnons

Abstract

In experiments and applications usually the spin magnetic moment of magnons is considered. In this Paper we identify an additional degree of freedom of magnons: an \emph{orbital} magnetic moment brought about by spin-orbit coupling.Our microscopic theory uncovers that spin magnetization ${\vec{M}}^{\mathrm{S}}$ and orbital magnetization ${\vec{M}}^{\mathrm{O}}$ are independent quantities. They are not necessarily collinear; thus, even when the total spin moment is compensated due to antiferromagnetism (${\vec{M}}^{\mathrm{S}}=\vec{0}$), ${\vec{M}}^{\mathrm{O}}$ may be nonzero. This scenario of orbital weak ferromagnetism is realized in paradigmatic kagome antiferromagnets with Dzyaloshinskii-Moriya interaction. We demonstrate that magnets exhibiting a magnonic orbital moment are omnipresent and propose transport experiments for probing it.

References in corpus (9)

• Spin Seebeck insulator
• Observation of the Magnon Hall Effect
• Theoretical prediction of rotating magnon wavepacket in ferromagnets
• Signature of magnon Nernst effect in an antiferromagnetic insulator
• Weak ferromagnetic order breaking the threefold rotational symmetry of the underlying kagomé lattice in CdCu${}_3$(OH)${}_6$(NO${}_3$)${}_2\cdot$H${}_2$O
• Spin wave spectrum of the quantum ferromagnet on the pyrochlore lattice Lu2V2O7
• Magnonic Analogue of Edelstein Effect in Antiferromagnetic Insulators
• Anisotropic magnetic excitations from single-chirality antiferromagnetic state in Ca-kapellasite
• Orbital Nernst Effect of Magnons