CaMn$_2$Sb$_2$: Spin waves on a frustrated antiferromagnetic honeycomb lattice

D. E. McNally; J. W. Simonson; J. J. Kistner-Morris; G. J. Smith; J. E. Hassinger; L. De-Beer-Schmitt; A. I. Kolesnikov; I. A. Zaliznyak; M. C. Aronson

doi:10.1103/PhysRevB.91.180407

paper

CaMn $_{2}$ Sb $_{2}$ : Spin waves on a frustrated antiferromagnetic honeycomb lattice

arXiv:1505.06153 · doi:10.1103/PhysRevB.91.180407

Abstract

We present inelastic neutron scattering measurements of the antiferromagnetic insulator CaMn $_{2}$ Sb $_{2}$ , which consists of corrugated honeycomb layers of Mn. The dispersion of magnetic excitations has been measured along the H and L directions in reciprocal space, with a maximum excitation energy of $\approx$ 24 meV. These excitations are well described by spin waves in a Heisenberg model, including first and second neighbor exchange interactions, J $_{1}$ and J $_{2}$ , in the Mn plane and also an exchange interaction between planes. The determined ratio J $_{2}$ /J $_{1}$ $\approx$ 1/6 suggests that CaMn $_{2}$ Sb $_{2}$ is the first example of a compound that lies very close to the mean field tricritical point, known for the classical Heisenberg model on the honeycomb lattice, where the Néel phase and two different spiral phases coexist. The magnitude of the determined exchange interactions reveal a mean field ordering temperature $\approx$ 4 times larger than the reported Néel temperature T $_{N}$ = 85 K, suggesting significant frustration arising from proximity to the tricritical point.

arXiv comment4 figures, 6 pages

CaMn $_{2}$ Sb $_{2}$ : Spin waves on a frustrated antiferromagnetic honeycomb lattice

Abstract

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CaMn2​Sb2​: Spin waves on a frustrated antiferromagnetic honeycomb lattice

Abstract

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Cited by in corpus (21)

CaMn $_{2}$ Sb $_{2}$ : Spin waves on a frustrated antiferromagnetic honeycomb lattice