Spin waves in the anisotropic fcc kagome antiferromagnet

Abstract

Spin wave calculations demonstrate that the macroscopic continuous degeneracy associated with the two-dimensional kagome Heisenberg spin lattice persists in the case of the stacked fcc structure giving rise to zero energy modes in three dimensions. The addition of an effective local cubic anisotropy is shown to remove this continuous degeneracy and introduce a gap in the spectrum as well as modify the inelastic scattering function $S(\mathbf{q},\omega )$. This scenario supports earlier Monte Carlo simulations which indicate that the phase transition to long range $q=0$ magnetic order is driven to be discontinuous by critical fluctuations associated with the large degeneracy in the absence of anisotropy, but becomes continuous with the addition of anisotropy. The results are relevant to Ir-Mn alloys which are widely used in the magnetic storage industry in thin film form as the antiferromagnetic pinning layer in spin-valve structures.

11 pages, 3 figures

References in corpus (5)

• Spin waves in the Frustrated Kagome Lattice Antiferromagnet KFe3(OH)6(SO4)2
• Quantum order by disorder and accidental soft mode Er2Ti2O7
• Giant magnetic anisotropy of the bulk antiferromagnets IrMn and IrMn3
• Fictitious excitations in the classical Heisenberg antiferromagnet on the kagome lattice
• Tricritical transition in the classical XY model on Kagomé lattice under local anisotropy

Cited by in corpus (2)

• Anisotropic magnetic interactions in hexagonal AB-stacked kagome lattice structures: Applications to ${\mathrm{Mn}}_3\mathrm{X}$ ($\mathrm{X}$ = $\mathrm{Ge}$, $\mathrm{Sn}$, $\mathrm{Ga}$) compounds
• Impact of Dzyaloshinskii-Moriya and anisotropic exchange interactions on the cubic kagome antiferromagnets Mn${}_3$X and Mn${}_3$AB