Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 7: Micro- and Nanostructured Magnetic Materials I
MA 7.9: Vortrag
Montag, 27. März 2006, 17:00–17:15, HSZ 03
Preparation of single-crystalline Fe nanopillars for Spin-Transfer Switching — •Henning Dassow, R. Lehndorff, D. E. Bürgler, M. Buchmeier, P. Grünberg, and C. M. Schneider — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
We report on the preparation of single-crystalline Fe nanopillars and on the first measurements of spin-transfer effects in this system. By using molecular beam epitaxy, we first deposit a layered magnetic system containing three Fe layers on top of a thick Ag buffer layer: Ag(150)/Fe(14)/Cr(0.9)/Fe(10)/Ag(6)/Fe(2) [thicknesses in nm]. The measurement of the Magneto Optical Kerr Effect (MOKE) yields the magnetic properties of the samples. In various cleanroom steps we fabricate nanopillars of a diameter of 150 nm by a combined optical / e-beam lithography technique in which the pillars are defined by Ion Beam Etching (IBE). Redeposition of etched material is observed with Atomic Force Microscopy (AFM) and can significantly broaden the structure. After planarization we open the isolation and contact the top of the nanopillar with lift-off of Au. The effect of dipolar stray fields can be estimated by comparison of the Giant Magneto Resistance (CPP-GMR) and MOKE hysteresis loops. The stray fields also have direct influence on the spin-transfer switching of the nanopillars which is observed at current densities of j∼ 2· 107 A/cm2 and can increase the critical current density by a factor of 10.