Magnetic evolution of Spinel Mn1-xZnxCr2O4 single crystals

TL;DR

This study investigates the structural and magnetic evolution of Mn1-xZnxCr2O4 single crystals across different doping levels, revealing transitions from ferrimagnetic to antiferromagnetic states due to Zn substitution.

Contribution

It provides detailed experimental insights into how Zn doping influences the magnetic phases and properties of MnCr2O4 spinel crystals, including the suppression of spiral ferrimagnetism and emergence of antiferromagnetism.

Findings

Lattice constant decreases with increasing Zn content following Vegard's law.

Magnetic ground state transitions from ferrimagnetic to antiferromagnetic with doping.

Spin glass behavior appears at intermediate doping levels.

Abstract

Mn1-xZnxCr2O4 (0<x<1) single crystals have been grown by the chemical vapor transport (CVT) method. The crystallographic, magnetic, and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, magnetization M(T) and specific heat CP(T) measurements. Mn1-xZnxCr2O4 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 Mn1-xZnxCr2O4 crystals has been discussed. For 0<x<0.3, the magnetic ground state is the coexistence of the collinear ferrimagnetic order (CFIM) and 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 (Cmag.) 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 Mn1-xZnxCr2O4 crystals have been discussed.