Regensburg 2016 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 12: Postersession DS

DS 12.39: Poster

Montag, 7. März 2016, 17:00–19:00, Poster A

MgO barrier parameter and TMR of PLD grown magnetic tunnel junctions with zinc ferrite electrodes — •Michael Bonholzer, Daniel Splith, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für experimentelle Physik II, Linnéstr. 5, 04103 Leipzig

We built zinc ferrite (ZnFe2O4) based magnetic tunnel junctions (MTJs) with an epitaxial MgO barrier and investigated their electrical properties.

A multilayer of TiN/ZnFe2O4/MgO/Co was deposited on (100)-MgO substrates by PLD. MTJs, lateral size ranging from 5×5 to 30×30 µm2, were defined by argon ion etching. A high quality, epitaxial TiN layer [1] is used to reduce series resistance. RHEED intensity oscillations, visible during PLD-growth of MgO, show the high structural quality of the barrier and allow an accurate determination of barrier thickness. With that, other barrier parameters were determined out of I-V measurements by a modified BDR-model [2]. Since the original BDR-model neglects the influence of lateral thickness variations, we introduced the barrier roughness as new parameter modelled by a Gaussian distribution of thickness and fixed the mean thickness to the value determined by RHEED. The new model gives reasonable values for roughness and height of the MgO barrier.

Magnetic field-dependent resistance measurements carried out on these structures show a TMR of 1% at 200 K.

[1] M. Bonholzer et al., Phys. Status Solidi A 211, 2621 (2014)
[2] W.F. Brinkman et al., J. Appl. Phys. 41, 1915 (1970)

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