Effect of Fe substitution on structure and exchange interactions within and between the sublattices of frustrated CoCr2O4

Abstract

Obtaining tunable magnetic states in geometrically frustrated multiferroic compound CoCr₂O₄ by tuning the sublattice magnetic coupling is indeed of high interest from the fundamental and applied points of view. In this work, Fe substitution effects in Co(Cr_1−xFe_x)₂O₄ (0 ≤ x ≤0.5) are experimentally investigated through detailed measurements of the crystalline structure and magnetization. Our experiments reveal that the samples undergo a magnetic transition characterized by a sharp variation in magnetization from 94 K at x = 0 to 317 K at x = 0.5. The field-cooled process shows that a magnetization reversal phenomenon is observed under a stable positive magnetic field when the measurement undergoes the compensation temperature. A magnetic field-assisted switching effect is realized near the compensation temperature, which possesses the characteristics of high repeatability and stability. The molecular field coefficients are evaluated based on the ferrimagnetic Curie–Weiss fitting, and the exchange interactions within and between the sublattices show a relationship of |J_AA| < |J_AB| < |J_BB|. The magnetization reversal in Co(Cr_1−xFe_x)₂O₄ is considered to be attributed to the coexistence and competition of A–A, A–B and B–B magnetic interactions, as well as the weakening of spin frustration.