Effect of spin dilution on the magnetic state of delafossite CuCrO ₂ with an S = 3/2 antiferromagnetic triangular sublattice

We investigated an effect of spin dilution on the magnetic and thermal properties of delafossite CuCrO₂ having an S = 3=2 antiferromagnetic triangular lattice (ATL) by the substitution of Al³⁺ for Cr ³⁺ by measurements of magnetization, specific heat, and neutron scattering. Spin defects introduced into Cr ATL layers blur the antiferromagnetic transition and induce a dimensional crossover of low-energy magnetic excitation in the residual Cr ATL region due to the reduction of inter-layer magnetic interaction, while accompanying an enhancement of a spin-glass component. The observed T² contribution to the low-T C_mag above y = 0:15, as well as in Cu_0:85Ag _0:15CrO₂, comes mainly from a short-range 2D AF excitation originating in a nontrivial magnetic state such as spin-nematic or spinliquid states.