Hole-doping effect on the magnetic state of delafossite oxide CuCrO₂

We investigated the substitution effects of Mg²⁺, Ca²⁺, and Al³⁺ for Cr³⁺ on the magnetic, transport and thermal properties of delafossite oxide CuCrO₂, which possesses a quasi-2D Heisenberg triangular antiferromagnetic (AF) lattice. Magnetization and specific heat measurements indicated that AF ordering is promoted by the substitution of nonmagnetic Mg²⁺ for Cr³⁺ (S = 3/2), despite the fact that a spin vacancy is introduced in a 120° spin structure at the Cr sites. These results suggest that the residual magnetic frustration is partially broken by spin fluctuations, which are enhanced through the interaction between the itinerant hole introduced by Mg doping and the localized spin at the Cr site.