From spin induced ferroelectricity to spin and dipolar glass in a triangular lattice: The CuCr1−V O2 (0≤x≤0.5) delafossite

Abstract

The change from antiferromagnetism induced ferroelectricity to spin glass ferroelectric relaxor has been studied along the CuCr 1− x V x O 2 (0≤ x ≤0.5) solid solution of polycrystalline samples. As x increases from CuCrO 2 ( x =0) to CuCr 0.82 V 0.18 O 2 , it is found that the Néel temperature decreases from ∼24 K down to ∼13 K. This progressive weakening of the antiferromagnetism of CuCrO 2 induces a rapid decrease of the spin induced ferroelectricity with polarization values going from ∼44 μC/m 2 down to ∼1.5 μC/m 2 for x =0.04 and x =0.08, respectively. Beyond x =0.18 (0.20≤ x ≤0.50), ac-magnetic susceptibility and magnetization measurements evidence a spin glass state while dielectric permittivity and polarization measurements point towards a relaxor behaviour. This shows that competing magnetic interactions in delafossites are an efficient way to transform a spin induced magnetoelectric into a multiglass (spin and dipolar) state. The P(T) curves evidencing the aging effect on polarization in CuCr 0.5 V 0.5 O 2 : E =135 kV/m is applied during cooling at different temperatures. The P values and the inflection point of the transition depend on the poling temperature suggesting a relaxor behaviour. This effect related to the spin glass state is not observed for the lowest vanadium content. • Samples of the CuCr 1− x V x O 2 series have been studied. • The V content increase induces a change from antiferromagnetism to spin glass. • A behavior characterisitic of a spin and dipole glass is demonstrated. • The ferroelectricity is shown to go from spin induced to relaxor. • Competing magnetic interactions are efficient way to generate multiglass state.