Effects of Ni Substitutions on the Critical Behaviors in $Nd_{0.6}Sr_{0.4}Mn_{1-x}Ni_{x}O_{3}$ Manganite

TL;DR

This study examines how Ni substitution affects the crystal structure and magnetic phase transition behavior of Nd0.6Sr0.4MnO3 manganite, revealing a shift from 3D-Heisenberg to mean-field critical behavior with increasing Ni content.

Contribution

It provides detailed analysis of structural and critical magnetic behavior changes due to Ni substitution in Nd0.6Sr0.4MnO3, highlighting a transition in universality class.

Findings

Ni substitution causes a linear decrease in lattice parameters.

Critical exponents shift from 3D-Heisenberg to mean-field behavior with Ni doping.

Universal scaling confirms the reliability of the critical exponents.

Abstract

We investigate the effect of Ni${\text -}$substitution on the crystalline structure and the critical behavior of $Nd_{0.6}Sr_{0.4}Mn_{1-x}Ni_{x}O_{3}$ (0.00 $\leq$ x $\leq$ 0.20) perovskite. X${\text -}$ray diffraction patterns revealed that the major phase in all samples is the orthorhombic structure with space group $\textit{Pnma}$. Rietveld refinement revealed a linear reduction in the lattice parameters along with monotonic reduction in the O2${\text -}$Mn${\text -}$O2 angel with increasing Ni concentration. The modified Arrott plots and the Kouvel${\text -}$Fisher method have been used to analyze the magnetization isotherms near the paramagnetic to ferromagnetic (PM${\text -}$FM) phase transition. The obtained critical exponents ($\beta$, $\gamma$ and $\delta$) revealed that the Ni${\text -}$free sample is consistent with 3D${\text -}$Heisenberg like behavior. However, upon Ni${\text -}$substitution, the critical exponents exhibit a mean field like behavior. The reliability of the obtained critical exponent ($\beta$, $\gamma$ and $\delta$) values have been confirmed by the universal scaling behavior of the isothermal magnetization near the transition temperature.