Gallium Substituted "114" YBaFe4O7: From a ferrimagnetic cluster glass to a cationic disordered spin glass

TL;DR

This study investigates how gallium substitution in YBaFe4O7 alters its magnetic properties, transitioning from a ferrimagnetic cluster glass to a cationic disordered spin glass, with phase separation and exchange bias effects.

Contribution

It reveals the evolution of magnetic states due to Ga doping, highlighting the transition from geometrically frustrated to cationic disorder spin glasses and associated phase separation phenomena.

Findings

Ga substitution stabilizes hexagonal symmetry

Transition from spin glass to cationic disordered spin glass

Presence of phase separation and exchange bias

Abstract

The study of the ferrites YBaFe4-xGaxO7 shows that the substitution of Ga for Fe in YBaFe4O7 stabilizes the hexagonal symmetry for 0.40 < x < 0.70, at the expense of the cubic one. Using combined measurements of a. c. and d. c. magnetization, we establish that Ga substitution for Fe in YBaFe4O7 leads to an evolution from a geometrically frustrated spin glass (for x = 0) to a cationic disorder induced spin glass (x = 0.70). We also find an intermediate narrow range of doping where the samples are clearly phase separated having small ferrimagnetic clusters embedded in a spin glass matrix. The origin of the ferrimagnetic clusters lies in the change in symmetry of the samples from cubic to hexagonal (and a consequent lifting of the geometrical frustration) as a result of Ga doping. We also show the presence of exchange bias and domain wall pinning in these samples. The cause of both these effects can be traced back to the inherent phase separation present in the samples.