Effect of Zn doping on the Magneto-Caloric effect and Critical Constants of Mott Insulator MnV2O4

TL;DR

This study investigates how Zn doping affects the magneto-caloric effect and critical magnetic properties of MnV2O4, revealing non-universal critical exponents and significant magneto-caloric effects influenced by orbital-spin coupling.

Contribution

It provides new insights into the critical behavior and magneto-caloric properties of Zn-doped MnV2O4, highlighting the impact of doping on orbital-spin interactions.

Findings

Critical exponents are non-universal, between 3D Heisenberg and mean field models.

Large magneto-caloric effects observed in all samples.

Zn doping alters orbital-spin coupling, affecting magnetic properties.

Abstract

X-ray absorption near edge spectra (XANES) and magnetization of Zn doped MnV2O4 have been measured and from the magnetic measurement the critical exponents and magnetocaloric effect have been estimated. The XANES study indicates that Zn doping does not change the valence states in Mn and V. It has been shown that the obtained values of critical exponents \b{eta}, {\gamma} and {\delta} do not belong to universal class and the values are in between the 3D Heisenberg model and the mean field interaction model. The magnetization data follow the scaling equation and collapse into two branches indicating that the calculated critical exponents and critical temperature are unambiguous and intrinsic to the system. All the samples show large magneto-caloric effect. The second peak in magneto-caloric curve of Mn0.95Zn0.05V2O4 is due to the strong coupling between orbital and spin degrees of freedom. But 10% Zn doping reduces the residual spins on the V-V pairs resulting the decrease of coupling between orbital and spin degrees of freedom.