Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.47: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Magnetoresistive effects in LSMO:MgO TMR-systems — •Markus Esseling¹, Stephanie Raabe¹, Vasily Moshnyagy¹, Achim Marx², Rudolf Gross², and Konrad Samwer¹ — ¹I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen — ²Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Str. 8, D-85748 Garching

The TMR effect is known to be very sensitive to the quality of the interface ferromagnet/insulator. The influence of the interfacial properties on the spin-dependent transport can be studied by using different ways to prepare the tunnel junction, namely i) a nanocomposite film consisting of ferromagnetic metallic grains separated by an insulator ii) a well defined grain-boundary of the ferromagnet doped with the insulator due to a chemical phase separation using a bicrystal-substrate and iii) an artificial multilayer structure. Using the highly spin-polarized manganite La_0.7Sr_0.3MnO₃ (LSMO) and the insulating MgO, which is an ideal candidate to achieve high TMR-values, it is possible to prepare these different systems mentioned above. We present results of the structural and electronic characterization of the bicrystal samples, which were prepared on symmetric 24^∘ [001] tilted SrTiO₃- and MgO-substrates to trigger an epitaxial growth of the LSMO on both sides of the grain-boundary of the bicrystal. The results are compared with the nanocomposite, which was characterized using low-frequency 1/f-noise measurements [1].

[1] M. Esseling et al., Appl. Phys. Lett. 87 (2005) 082509

Supported by SFB 602, TP A2 and DFG Sa 339/9