Influence of Mg, Ag and Al substitutions on the magnetic excitations in the triangular-lattice antiferromagnet CuCrO2

TL;DR

This study investigates how substituting Mg, Ag, and Al in CuCrO2 affects its magnetic excitations, revealing changes in spin dynamics and the emergence of low-energy fluctuations through neutron scattering experiments.

Contribution

It provides new insights into the element substitution effects on magnetic excitations in the triangular-lattice antiferromagnet CuCrO2, highlighting the roles of doped holes and magnetic dimensionality.

Findings

Mg substitution retains dispersive and flat excitation components with some spectral differences.

Ag and Al substitutions reduce flat components and enhance low-energy spin fluctuations.

Substitution effects are linked to hole doping and changes in magnetic correlation dimensionality.

Abstract

Magnetic excitations in CuCrO$_{2}$, CuCr$_{0.97}$Mg$_{0.03}$O$_{2}$, Cu$_{0.85}$Ag$_{0.15}$CrO$_{2}$, and CuCr$_{0.85}$Al$_{0.15}$O$_{2}$ have been studied by powder inelastic neutron scattering to elucidate the element substitution effects on the spin dynamics in the Heisenberg triangular-lattice antiferromagnet CuCrO$_{2}$. The magnetic excitations in CuCr$_{0.97}$Mg$_{0.03}$O$_{2}$ consist of a dispersive component and a flat component. Though this feature is apparently similar to CuCrO$_{2}$, the energy structure of the excitation spectrum shows some difference from that in CuCrO$_{2}$. On the other hand, in Cu$_{0.85}$Ag$_{0.15}$CrO$_{2}$ and CuCr$_{0.85}$Al$_{0.15}$O$_{2}$ the flat components are much reduced, the low-energy parts of the excitation spectra become intense, and additional low-energy diffusive spin fluctuations are induced. We argued the origins of these changes in the magnetic excitations are ascribed to effects of the doped holes or change of the dimensionality in the magnetic correlations.