Dresden 2006 – scientific programme

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MA: Magnetismus

MA 25: Spin-Electronics I

MA 25.10: Talk

Thursday, March 30, 2006, 12:30–12:45, HSZ 103

Spin-filtering through multiferroic BiMnO₃ tunnel barriers — •Manuel Bibes¹, Martin Gajek², Martin Sirena², Gervasi Herranz², Karim Bouzehouane², Stéphane Fusil³, Manuel Varela⁴, Josep Fontcuberta⁵, Agnès Barthélémy², and Albert Fert² — ¹Institut d’Electronique Fondamentale, Université Paris-Sud, 91405 Orsay, France — ²Unité Mixte de Physique CNRS-Thales, Route départementale 128, 91767 Palaiseau, France — ³Université d’Evry, rue du Père Jarlan, 91025 Evry, France — ⁴Dept. de Fisica Aplicada i Optica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain — ⁵Institut de Ciència de Materials de Barcelona, CSIC, Campus de la UAB, 08193 Bellaterra, Spain

We will present the properties of BiMnO₃ (BMO) and La_0.1Bi_0.9MnO₃ (LBMO) epitaxial thin films grown onto conductive buffers like La_2/3Sr_1/3MnO₃ (LSMO). Both BMO and LBMO films are ferromagnetic and piezoresponse atomic-force microscopy also evidences their ferroelectric character, thereby confirming their multiferroic nature. Remarkably, these properties are preserved even for films a few nm thick that can thus be used as multiferroic tunnel barriers. We will show that tunneling from a Au electrode, through these ferromagnetic tunnel barriers, into a collecting ferromagnetic counter-electrode of LSMO, results in large tunnel magnetoresistance (TMR), observed upon switching the magnetic configuration of the barrier and LSMO magnetizations from parallel or antiparallel. This demonstrates a spin-filtering effect by the BMO and LBMO barriers. The possible influence of ferroelectricity on the tunnel process will also be discussed.