Oxide Heterostructures Based on Fe3O4 Thin Films

Andrius Maneikis 1,2Bonifacas Vengalis 1Kristina Šliužienė 1Vaclovas Lisauskas 1Antanas Oginskis 1Leonas Dapkus 1

1. Semiconductor Physics Institute, A.Gostauto 11, Vilnius LT-2600, Lithuania
2. Vilnius Gediminas Technical University, Sauletekio al. 11, Vilnius LT-2040, Lithuania

Abstract

Ferrimagnetic magnetite, Fe3O4, is a promising material for spin dependent electronics due to high Curie temperature (of 858 K) and high degree of spin polarized carriers at room temperature. Up to now, high quality Fe3O4 films have been grown heteroepitaxially on latticed-matched MgO, SrTiO3 and Al2O3. However, for most applications such as tunneling magnetoresistance (TMR) devices there is great interest in various heterostructures composed of lattice-matched ferromagnetic, antiferromagnetic films, highly conducting underlayers and insulating barrier layers.

In this work, Fe3O4 thin films were grown on both lattice matched MgO or Al2O3 substrates and La2/3A1/3MnO3 (A = Ca, Sr, Ce) underlayers by DC magnetron sputtering of metallic Fe target under a fixed Ar:O2 (30:1) gas mixture pressure of about 5 Pa. The manganite films were prepared by the same method on both lattice-matched SrTiO3 and NdGaO3 buffered by highly conductive LaNiO3 or RuO2 layers. Crystalline structure of all the films and heterostructures were characterized by x-ray difraction (XRD) and reflected high-energy electron diffraction (RHEED). The electrical resistance, magnetoresistance and voltage versus current were measured for the films and multilayer structures in a wide range of temperatures and magnetic fields. Three point-probe method was applied to investigate the interface resistance and tunneling magnetoresistance of the heterostructures. Electrical properties of the interfaces were modelled to elucidate the effect of deposition conditions and possible oxygen diffusion at various interfaces.

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Presentation: poster at E-MRS Fall Meeting 2005, Symposium D, by Andrius Maneikis
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-30 13:39
Revised:   2009-06-07 00:44
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