Development of spin correlations in the geometrically frustrated triangular-lattice Heisenberg antiferromagnet CuCrO₂

Magnetic excitations in the triangular-lattice Heisenberg antiferromagnet CuCrO₂ were studied using single-crystal inelastic neutron scattering. A diffusive quasielastic component that persisted without developing a correlation length over a wide temperature range both below and above the ordering temperature was observed. Furthermore, characteristic momentum dependence was observed that was reproduced using minimum spin clusters. The robust spin clusters contrast with conventional magnetic ordering and may be universal in triangular-lattice Heisenberg antiferromagnets.