Frustration enhanced by Kitaev exchange in a ${\tilde{\mathbf{j}}}_{\text{eff}}=\frac{1}{2}$ triangular antiferromagnet

Abstract

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 of ${\tilde{j}}_{\text{eff}}=\frac{1}{2}$ 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 the ${\tilde{j}}_{\text{eff}}=\frac{1}{2}$ ground state, theory identifies ferromagnetic Kitaev exchange anisotropy as additional frustrating agent, altogether putting forward Na${}_2$BaCo(PO${}_4$)${}_2$ as a promising Kitaev spin-liquid material.

6 pages, 4 figures (published version) + supplemental material (4 pages)

References in corpus (6)

• Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO4
• Pseudospin exchange interactions in d^7 cobalt compounds: Possible realization of the Kitaev model
• Weak-field induced nonmagnetic state in a Co-based honeycomb
• Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice
• Crystal field theory of Co${}^{2+}$ in doped ZnO
• Schwinger boson mean field study of the $J_1$-$J_2$ Heisenberg quantum antiferromagnet on the triangular lattice

Cited by in corpus (3)

• Double magnetic transitions and exotic field induced phase in the triangular lattice antiferromagnets Sr${}_3$Co(Nb,Ta)${}_2$O${}_9$
• Static magnetic and ESR spectroscopic properties of the dimer-chain antiferromagnet BiCoPO${}_5$
• Doping-induced structural transformation in the spin-1/2 triangular-lattice antiferromagnet Na${}_2$Ba${}_{1-x}$Sr${}_x$Co(PO${}_4$)${}_2$