Measuring the three-dimensional structure of ultrathin insulating films at the atomic scale.

Baumann, Susanne; Rau, Ileana G; Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J · ACS Nano · 2014

basic_science · Level V

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Abstract

The increasing technological importance of thin insulating layers calls for a thorough understanding of their structure. Here we apply scanning probe methods to investigate the structure of ultrathin magnesium oxide (MgO) which is the insulating material of choice in spintronic applications. A combination of force and current measurements gives high spatial resolution maps of the local three-dimensional insulator structure. When force measurements are not available, a lower spatial resolution can be obtained from tunneling images at different voltages. These broadly applicable techniques reveal a previously unknown complexity in the structure of MgO on Ag(001), such as steps in the insulator-metal interface.