Magnetic evolution of spinel Mn1−xZnxCr2O4 single crystals

Abstract

Mn_1−xZn_xCr₂O₄ (0 ≤ x ≤ 1) single crystals have been grown using the chemical vapor transport (CVT) method. The crystallographic, magnetic, and thermal transport properties of the single crystals were investigated by room-temperature X-ray diffraction, magnetization M(T) and specific heat C_P(T) measurements. Mn_1−xZn_xCr₂O₄ crystals show a cubic structure, the lattice constant a decreases with the increasing content x of the doped Zn²⁺ ions and follows the Vegard law. Based on the magnetization and heat capacity measurements, the magnetic evolution of Mn_1−xZn_xCr₂O₄ crystals has been discussed. For 0 ≤ x ≤ 0.3, the magnetic ground state is the coexistence of the long-range ferrimagnetic order (LFIM) and the spiral ferrimagnetic one (SFIM), which is similar to that of the parent MnCr₂O₄. When x changes from 0.3 to 0.8, the SFIM is progressively suppressed and spin glass-like behavior is observed. When x is above 0.8, an antiferromagnetic (AFM) order presents. At the same time, the magnetic specific heat (C_mag.) was also investigated and the results are coincident with the magnetic measurements. The possible reasons based on the disorder effect and the reduced molecular field effect induced by the substitution of Mn²⁺ ions by nonmagnetic Zn²⁺ ones in Mn_1−xZn_xCr₂O₄ crystals have been discussed.