Growth and investigation of oxide heterostructures containing half-metallic Fe3O4

Bonifacas Vengalis 1Lisauskas Vaclovas 1Kristina Sliuziene 1Vytautas Petrauskas 1Sebastiaan Van Dijken 2Mazhar Bari 2M Venkatesan 2Mike Coey 2

1. Semiconductor Physics Institute, A.Gostauto 11, Vilnius LT-2600, Lithuania
2. Trinity College, Deptartment of Physics, College Green, Dublin Dublin 2, Ireland

Abstract

Magnetite, 'Fe3O4', with an inverse cubic spinel structure (a=0.8396 nm ) is known as a ferrimagnetic oxide exhibiting electrical conductivity due to hopping of spin-polarized electrons between ferrimagnetically ordered Fe2+ and Fe3+states. It is promising for novel applications based on spin-polarized transport due mainly to high Curie temperature ('Tc' = 858 K) which is an important advantage compared to other half-metallic oxides such as 'La1-xSrxMnO3' (360 K), 'Sr2FeMoO6' (450 K), 'CrO2' (395 K). For most of the applications, there is increasing need of fundamental and technological research of various hybrid device structures composed of high quality 'Fe3O4' layers, conducting underlayers and isolating barriers. In this work, thin films of 'Fe3O4' were grown in-situ at T=300-500oC on both lattice-matched MgO and epitaxial conductive ITO/YSZ(100), 'LaNiO3'/'NdGaO3'(100),'La0.66(Ca,Sr)0.34O3'/'NdGaO3' underlayers by sputtering of metallic Fe target under a fixed Ar:'O2' (30:1) gas mixture pressure of about 5 Pa. Reflected high energy electron diffraction (RHEED) and XRD investigations revealed epitaxial quality of the magnetite films grown on MgO and ITO/YSZ meanwhile the films prepared on perovskite underlayers were highly textured. We were focussing on in- and out-of-plane resistivity, resistance anomaly at the Vervey transition point ('TV' = 120 K), magnetoresistance, magnetization and current versus voltage to elucidate the effect of substrate and deposition conditions on major parameters of the grown 'Fe3O4' films and to investigate interface properties of the 'Fe3O4'/'In2O3'<Sn>, 'Fe3O4'/'LaNiO3' and 'Fe3O4'/'La0.66(Ca,Sr)0.33O3' heterostructures. Current flow in the bilayer structures was modeled to investigate stability of the interfaces and to evaluate diffusion of oxygen in different layers.

 

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Presentation: poster at E-MRS Fall Meeting 2003, Symposium F, by Bonifacas Vengalis
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 18:49
Revised:   2009-06-08 12:55