Effect of Spin Dilution on the Magnetic State of Delafossite CuCrO2 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 Cr3+ 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 T-2 contribution to the low-T C-mag above y = 0.15, as well as in Cu0.85Ag0.15CrO2, comes mainly from a short-range 2D AF excitation originating in a nontrivial magnetic state such as spin-nematic or spin-liquid states.