Dilute ferrimagnetic semiconductors in Fe-substituted spinel ZnGa$_2$O$_4$

TL;DR

This study demonstrates that Fe substitution in ZnGa₂O₄ creates dilute ferrimagnetic semiconductors with long-range magnetic order at low temperatures, maintaining semiconducting properties and opening avenues for spintronic applications.

Contribution

The paper reports the synthesis and characterization of Fe-substituted ZnGa₂O₄ spinels exhibiting ferrimagnetic order without compromising their semiconducting behavior, a novel combination for potential spintronic devices.

Findings

Long-range magnetic ordering observed at low temperatures.

Fe substitution up to x=0.15 does not alter the band edge absorption.

Magnetic hysteresis and spontaneous magnetization confirmed.

Abstract

Solid solutions of nominal composition [ZnGa$_2$O$_4$]$_{1-x}$[Fe$_3$O$_4$]$_x$, of the semiconducting spinel ZnGa$_2$O$_4$ with the ferrimagnetic spinel Fe$_3$O$_4$ have been prepared with $x$ = 0.05, 0.10, and 0.15. All samples show evidence for long-range magnetic ordering with ferromagnetic hysteresis at low temperatures. Magnetization as a function of field for the $x$ = 0.15 sample is S-shaped at temperatures as high as 200 K. M\"ossbauer spectroscopy on the $x$ = 0.15 sample confirms the presence of Fe$^{3+}$, and spontaneous magnetization at 4.2 K. The magnetic behavior is obtained without greatly affecting the semiconducting properties of the host; diffuse reflectance optical spectroscopy indicates that Fe substitution up to $x$ = 0.15 does not affect the position of the band edge absorption. These promising results motivate the possibility of dilute ferrimagnetic semiconductors which do not require carrier mediation of the magnetic moment.