Etching of Cr tips for scanning tunneling microscopy of cleavable oxides

Abstract

We report a detailed three-step roadmap for the fabrication and characterization of bulk Cr tips for spin-polarized scanning tunneling microscopy. Our strategy uniquely circumvents the need for ultra-high vacuum preparation of clean surfaces or films. First, we demonstrate the role of $ex$-$situ$ electrochemical etch parameters on Cr tip apex geometry, using scanning electron micrographs of over 70 etched tips. Second, we describe the suitability of the $in$-$situ$ cleaved surface of the layered antiferromagnet La${}_{1.4}$Sr${}_{1.6}$Mn${}_2$O${}_7$ to evaluate the spin characteristics of the Cr tip, replacing the UHV-prepared test samples that have been used in prior studies. Third, we outline a statistical algorithm that can effectively delineate closely-spaced or irregular cleaved step edges, to maximize the accuracy of step height and spin-polarization measurements.

10 pages, 10 figures, main text and supplementary material

References in corpus (5)

• Imaging Oxygen Defects and their Motion at a Manganite Surface
• Bilayer manganites: polarons in the midst of a metallic breakdown
• Bulk Cr tips for scanning tunneling microscopy and spin-polarized scanning tunneling microscopy
• Orbital mixing and nesting in the bilayer manganites La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$
• Electronic and magnetic influences of a stacking fault in cobalt nanoscale islands on the Ag(111) surface

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• Antiferromagnetic MnNi tips for spin-polarized scanning probe microscopy