Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.89: Poster

Freitag, 26. März 2010, 11:00–14:00, Poster B1

Transport properties of La_0.7R_0.3MnO₃/SrTiO₃/La_0.7R_0.3MnO₃ (R = Ca, Sr) magnetic tunnel junctions — •Patryk Nowik-Boltyk¹, Robert Werner¹, Lucero Alvarez², A. Yu. Petrov², Bruce A. Davidson², Reinhold Kleiner¹, and Dieter Koelle¹ — ¹Physikalisches Institut – Experimentalphysik II and Center for Collective Quantum Phenomena and their Applications, Universität Tübingen, Auf der Morgenstelle 14, D-72076, Germany — ²INFM-TASC National Laboratory, Area Science Park, S.S. 14, Km 163.5, I-34012 Basovizza (TS), Italy

Half metals like the doped manganites La_0.7Ca_0.3MnO₃ (LCMO) and La_0.7Sr_0.3MnO₃ (LSMO) are promising candidates for a very large tunneling magnetoresistance (TMR) effect due to their almost 100% spin-polarisation. However, weakening of the magnetic properties at the ferromagnet/insulator interfaces can cause a suppression of the TMR effect in magnetic tunnel junctions (MTJs) made of doped manganites. By introducing a doping profile in LRMO at the interface, the Mn valence can be controlled and the magnetization can be reinforced. We present results on the TMR in planar MTJs grown with different SrTiO₃ (STO) barrier thicknesses, as well as with different doping profiles within a few monolayers of LRMO at the interface. The LCMO trilayers were prepared using pusled laser deposition (PLD) while the LSMO trilayers were grown by molecular beam epitaxy (MBE). The MTJs where investigated in a temperature range T=4.2−300 K and characterized by differential conductance G vs voltage V and resistance R vs H measurements at different bias voltages.