Geometric and disorder -- type magnetic frustration in ferrimagnetic "114" Ferrites: Role of diamagnetic Li+ and Zn2+ cation substitution

TL;DR

This study investigates how diamagnetic Li+ and Zn2+ cation substitutions influence magnetic frustration and ferrimagnetism in

Contribution

It reveals the role of diamagnetic cations in tuning magnetic phases and structural transitions in

Findings

Li and Zn doping induce structural transitions from cubic to hexagonal phases.

Low doping levels enhance ferrimagnetism, contrasting with spin glass behavior in undoped phases.

High doping levels lead to spin glass states driven by cationic disorder.

Abstract

The comparative study of the substitution of zinc and lithium for iron in the "114" ferrites, YBaFe4O7 and CaBaFe4O7, shows that these diamagnetic cations play a major role in tuning the competition between ferrimagnetism and magnetic frustration in these oxides. The substitution of Li or Zn for Fe in the cubic phase YBaFe4O7 leads to a structural transition to a hexagonal phase YBaFe4-xMxO7, for M = Li (0.30 < x < 0.75) and for M = Zn (0.40 < x < 1.50). It is seen that for low doping values i.e. x = 0.30 (for Li) and x = 0.40 (for Zn), these diamagnetic cations induce a strong ferrimagnetic component in the samples, in contrast to the spin glass behaviour of the cubic phase. In all the hexagonal phases, YBaFe4-xMxO7 and CaBaFe4-xMxO7 with M = Li and Zn, it is seen that in the low doping regime (x ~ 0.3 to 0.5), the competition between ferrimagnetism and 2 D magnetic frustration is dominated by the average valency of iron. In contrast, in the high doping regime (x ~ 1.5), the emergence of a spin glass is controlled by the high degree of cationic disorder, irrespective of the iron valency.