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Abstract:
Solid solutions of nominal composition [ZnGa2O4](1-x)[Fe3O4](x), of the
semiconducting spinel ZnGa2O4 with the ferrimagnetic spinel Fe3O4, 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. The magnetization as a function of field for the x = 0.15
sample is S-shaped at temperatures as high as 200 K. Mossbauer
spectroscopy of the x = 0.15 sample confirms the presence of Fe3+, and
spontaneous magnetization at 4.2 K. The magnetic behaviour 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 us to suggest the possibility of dilute
ferrimagnetic semiconductors which do not require carrier mediation of
the magnetic moment.
