Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Magnetic Coupling Phenomena/ Exchange Bias

MA 33.1: Hauptvortrag

Mittwoch, 28. März 2012, 15:00–15:30, EB 202

Exchange bias and domain evolution at 10 nm scales — •Hans J. Hug^1,2, Miguel A. Marioni¹, Sara Romer¹, Sevil Oezer², and Niraj Joshi^1,2 — ¹Empa - Swiss Federal Laboratories for Materials Testing and Research, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland — ²Department of Physics, University of Basel, CH-4056 Basel, Switzerland

An obstacle to understanding the EB effect is that only a subset of the UCS (those pinned and coupled to the F) are responsible for the EB effect. Experimental methods that measure the pinUCS density distribution with spatial resolution comparable to the materials grain size are needed. Here we use quantitative, high-resolution magnetic force microscopy (MFM) to measure the local areal density of pinned uncompensated spins (pinUCS) and to correlate the F-domain structure in a perpendicular anisotropy CoPt multilayer with the pinUCS density [1]. Larger applied fields drive the receding domains to areas of proportionally higher pinUCS aligned antiparallel to F-moments. This confirms our prior results [2] that these antiparallel pinUCS are responsible for the EB effect, while parallel pinUCS coexist. The data confirm that the evolution of the F-domains is determined by the pinUCS in the AF-layer, and also present examples of frustration in the system. Grain-boundary engineering can be used to decouple the AF grains leading to a stronger EB-effect but a smaller coercivity. New types of thin film system showing and exchange bias field of 1T will be discussed. [1] I. Schmid et al. EPL, 81 (2008) 17001 [2] I. Schmid et al. PRL, 105 (2010) 197201