Topography-based navigation in a millikelvin scanning tunneling microscope using binary-encoded position markers

Abstract

We present a compact millikelvin scanning tunneling microscope (STM) operating at 270mK with topographic navigation to micron-scale targets. Two piezoelectric low-temperature nanopositioners extend the accessible sample area, while a multi-stage copper powder and capillary filter scheme preserves millikelvin energy resolution, verified by BCS spectroscopy on aluminium thin films. A lithographically fabricated binary-encoded gold pattern encodes unique 16-bit coordinates in 4x4 pixels of 200nm$\times$200nm each. We demonstrate absolute positioning across a 350$\times$350$\mathrmμ$m$^2$ area from a single STM scan. Requiring only a single lithography step and no hardware modifications to existing STM setups, the navigation system provides a versatile platform for scanning tunneling spectroscopy of nanoflakes and nanoscale devices.