Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 62: Magnetic Imaging
MA 62.3: Vortrag
Freitag, 18. März 2011, 11:15–11:30, HSZ 04
Morphological, electronic and magnetic characterization of bulk Cr tips — •Marco Corbetta1, Safia Ouazi1, Fabio Donati1,2, Yasmine Nahas1, Hirofumi Oka1, Sebastian Wedekind1, Dirk Sander1, and Jürgen Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany — 2CNISM, NEMAS and Dipartimento di Energia - Politecnico di Milano, Milano, Italy
The most delicate task for successful SP-STM measurements is the preparation of suitable tips offering high spatial resolution, high spin polarization and negligible magnetic stray field. Nonmagnetic tips covered with an ultrathin film of antiferromagnetic material as Cr have been largely and successfully used [1]. The main drawback of coated tips is that an in-situ preparation is required. Recently a simple and reliable method for the preparation of bulk Cr tips using only a standard electrochemical etching has been proposed [2]. We produced and used such tips for in-field spin-polarized STM measurements at 7 K on Co nano-islands on Cu(111). We obtain stable and reliable spin-resolved imaging and spectroscopy results. We measure symmetric hysteresis loops of the differential conductance, which show that the magnetization direction of the Cr tip apex follows the external magnetic field direction. Measuring dI/dV asymmetry curves on Co islands we find that the spin polarization of bulk Cr tips can be as large as 30%, which is larger as compared to Cr/Co/W tips [3]. [1] A. Kubetzka et al., Phys. Rev. Lett. 88, 057201 (2002). [2] A. Li Bassi et al., Appl. Phys. Lett. 91, 173120 (2007). [3] H. Oka et al., Science 327, 843 (2010).