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

スピン3/2を持つ三角格子反強磁性体CuCrOの磁性に対するスピン希釈効果

奥田 哲治*; 宇都 数馬*; 関 真一郎*; 小野瀬 佳文*; 十倉 好紀*; 梶本 亮一  ; 松田 雅昌*

Okuda, Tetsuji*; Uto, Kazuma*; Seki, Shinichiro*; Onose, Yoshinori*; Tokura, Yoshinori*; Kajimoto, Ryoichi; Matsuda, Masaaki*

We investigated an effect of spin dilution on the magnetic and thermal properties of delafossite CuCrO having an = 3/2 antiferromagnetic triangular lattice (ATL) by the substitution of Al for Cr 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 contribution to the low- above = 0.15, as well as in CuAgCrO, comes mainly from a short-range 2D AF excitation originating in a nontrivial magnetic state such as spin-nematic or spin-liquid states.