Frustration enhanced by Kitaev exchange in a j̃eff=12 triangular antiferromagnet
Résumé
Triangular Heisenberg antiferromagnets are prototypes of geometric frustration, even if for nearest-neighbor interactions quantum fluctuations are not usually strong enough to destroy magnetic ordering: stronger frustration is required to stabilize a spin-liquid phase. On the basis of static magnetization and electron spin resonance measurements, we demonstrate the emergence ofj eff = 1 2 moments in the triangular-lattice magnet Na 2 BaCo(PO 4) 2. These moments are subject to an extra source of frustration that causes magnetic correlations to set in far above both the magnetic ordering and Weiss temperatures. Corroborating thej eff = 1 2 ground state, theory identifies ferromagnetic Kitaev exchange anisotropy as an additional frustrating agent, altogether putting forward Na 2 BaCo(PO 4) 2 as a promising Kitaev spin-liquid material.
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