Influence of Fe and Cr doping on the structural and magnetic properties of ZnV2O4

Abstract

In this paper, we report the modulation of structural and magnetic properties with Fe and Cr doping at the Zn and V sites in ZnV2O4. Undoped ZnV2O4 exhibits two anomalies in the M–T measurements which are assigned to a structural transition (TS ~ 57 K) followed by a magnetic transition (TN ~ 41 K). With the help of x-ray diffraction and energy dispersive x-ray analysis it is found that the prepared samples are single phase as well as stoichiometric. However, doping at both the cationic sites of ZnV2O4 leads to the disappearance of the structural transition and suppression of the long range magnetic ordering to a cusp like feature below 20 K and the cusps broaden with increasing magnetic field while the position of the cusps remain unaltered with increasing field strength. The obtained results indicate that Zn1−xFexV2O4 and Zn(V1−tCrt)2O4 (x = t = 0, 0.05, 0.1) systems are frustrated cubic normal spinel systems. Moreover, such field independent behavior of cusp positions hints towards the antiferromagnetic ground state at low temperature instead of a spin glass phase. To elucidate this fact, dc aging (magnetic relaxation) and memory effects have been investigated in zero field cooled (ZFC) and field cooled (FC) protocol for the 10% doped samples, which exhibit aging and memory effect. Our study provides an explicit evidence of spin glass like state instead of low temperature antiferromagnetic ground state in the doped compounds.