Investigating the magnetic field-dependent conductivity in magnetite thin films by modelling the magnetorefractive effect

TY - JOUR

T1 - Investigating the magnetic field-dependent conductivity in magnetite thin films by modelling the magnetorefractive effect

AU - Kelley, C.S.

AU - Naughton, J.

AU - Benson, E.

AU - Bradley, R.C.

AU - Lazarov, V.K.

AU - Thompson, S.M.

AU - Matthew, J.A.D.

N1 - © 2014 IOP Publishing Ltd.

PY - 2014/1/22

Y1 - 2014/1/22

N2 - A model of the magnetorefractive effect is developed for metallic oxides which allows the MRE to be used to study the magnetic dependence of their transport and phononic properties. This model is successfully applied to Fe3O4 and compared to experiments on a series of magnetite thin films of varying thickness (10, 18, 37, 64 and 110 nm) deposited on MgO(111) substrates. Reflection spectra were modelled as a function of film thickness, calculated from the Fresnel equations using an Fe3O4 dielectric function consisting of Drude, hopping, phononic and d-s transition conductivity processes. The reflectivity spectra of the different thickness films are reasonably reproduced by the model and reveal that the Fe3O4 18.5 μm phonon peak is shifted to a shorter wavelength in the thin films, approaching the bulk value for t > 110 nm. The MRE spectra are modelled by introducing a magnetic field dependence to the hopping and phononic terms, where previous models have considered the magnetic dependence to be on the Drude term only. In addition, the position of the Fe3O4 18.5 μm phonon peak was also found to shift in energy in the applied magnetic field by 0.05 μm. These results demonstrate the potential for using the MRE technique for probing the underlying magnetoelectronic properties of thin film oxides in a quick and non-destructive way.

AB - A model of the magnetorefractive effect is developed for metallic oxides which allows the MRE to be used to study the magnetic dependence of their transport and phononic properties. This model is successfully applied to Fe3O4 and compared to experiments on a series of magnetite thin films of varying thickness (10, 18, 37, 64 and 110 nm) deposited on MgO(111) substrates. Reflection spectra were modelled as a function of film thickness, calculated from the Fresnel equations using an Fe3O4 dielectric function consisting of Drude, hopping, phononic and d-s transition conductivity processes. The reflectivity spectra of the different thickness films are reasonably reproduced by the model and reveal that the Fe3O4 18.5 μm phonon peak is shifted to a shorter wavelength in the thin films, approaching the bulk value for t > 110 nm. The MRE spectra are modelled by introducing a magnetic field dependence to the hopping and phononic terms, where previous models have considered the magnetic dependence to be on the Drude term only. In addition, the position of the Fe3O4 18.5 μm phonon peak was also found to shift in energy in the applied magnetic field by 0.05 μm. These results demonstrate the potential for using the MRE technique for probing the underlying magnetoelectronic properties of thin film oxides in a quick and non-destructive way.

UR - http://www.scopus.com/inward/record.url?scp=84892179486&partnerID=8YFLogxK

U2 - 10.1088/0953-8984/26/3/036002

DO - 10.1088/0953-8984/26/3/036002

M3 - Article

AN - SCOPUS:84892179486

SN - 0953-8984

VL - 26

JO - Journal of physics : Condensed matter

JF - Journal of physics : Condensed matter

IS - 3

M1 - 036002

ER -