Tunable magnetic excitations in the honeycomb antiferromagnet (Co,Ni)⁢TiO3

Rathnayaka, Srimal [University of Virginia, Charlottesville, VA]; Daemen, Luke [ORNL]; Calder, Stuart [ORNL] (ORCID:0000000184023741); Louca, Despina [University of Virginia]

doi:10.1103/stcc-25p1

DOE OSTI · 3682435

Tunable magnetic excitations in the honeycomb antiferromagnet (Co,Ni)⁢TiO3

Rathnayaka, Srimal [University of Virginia, Charlottesville, VA]·Daemen, Luke [ORNL]·Calder, Stuart [ORNL] (ORCID:0000000184023741)·Louca, Despina [University of Virginia]

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Abstract

The solid solution of the honeycomb antiferromagnet (AFM) Co0.5⁢Ni0.5⁢TiO3 (CNTO) was synthesized by mixing a 1:1 molar ratio of CoTiO3 (CTO) and NiTiO3 (NTO). Powder neutron scattering was used to determine the structure and magnetic spectrum, where the nuclear and magnetic structures resemble those of the end members. The Néel temperature (T𝑁 = 27 ± 1 K), the ordered magnetic moment (M = 2.29 ± 0.03 𝜇𝐵 per magnetic ion), and lattice parameters are intermediate between those of the two. From inelastic neutron scattering, it is observed that the magnon density of states (MDOS) extends up to 13 meV, and the interaction can be described by an XXZ-type magnetic Hamiltonian. Above 15 meV, spin-orbit excitons (SOEs) are observed similarly to those in CTO, but with modified spin-orbit crystal-field splitting because of the substitution of Ni at Co sites, and the disorder induced by the Ni substitution modifies the spin-orbit crystal field. Thus, the magnetic dynamics of the CNTO cannot be described as a simple average of the two parent compounds.

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Rathnayaka, Srimal [University of Virginia, Charlottesville, VA], Daemen, Luke [ORNL], Calder, Stuart [ORNL] (ORCID:0000000184023741), Louca, Despina [University of Virginia]. 2026-05-01. Tunable magnetic excitations in the honeycomb antiferromagnet (Co,Ni)⁢TiO3. https://doi.org/10.1103/stcc-25p1

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