Dresden 2006 – scientific programme

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MA: Magnetismus

MA 3: Spin-Dependent Transport Phenomena I

MA 3.1: Talk

Monday, March 27, 2006, 10:15–10:30, HSZ 103

Characterisation of ion beam sputtered Fe/MgO/Fe magnetic tunnel junction — •Alexandra Steeb, Henning Dassow, Diana Rata, Franz-Josef Köhne, Daniel Bürgler, and Claus M. Schneider — Institute for solid state research, Electronic Properties, Research Centre Jülich

The tunnel magnetoresistance effect (TMR) in magnetic tunnel junctions (MTJs) is the key to developing magnetoresistive random-access-memory. In single-crystal Fe/MgO/Fe MTJs prepared by MBE a TMR up to 180% at room temperature was measured [1]. The sputtered polycrystalline CoFe/MgO/CoFe MTJs exhibit TMR values of up to 220% at room temperature [2]. We report on Fe/MgO/Fe trilayers prepared by ion beam sputtering in ultra high vacuum conditions. Using the crystalline GaAs substrate the trilayers grow epitaxially as confirmed by LEED. We work with 300Å Fe/25Å MgO/100Å Fe samples, the MgO layer is sputtered directly from a MgO target. With XPS we proved, that there is no FeO between the Fe and MgO layers. To apply an exchange bias on the upper Fe layer, an antiferromagnetic layer FeMn is deposited on the trilayer. After post-annealing 1h@250^∘C we found a typically exchange bias field of 50 mT. First TMR measurements on this single crystalline TMR structures will be presented.

[1] S. Yuasa et al. Nature Materials 3, 868 (2004)

[2] S. Parkin et al. Nature Materials 3, 862 (2004)