Magnetic, Thermal, and Topographic Imaging with a Nanometer-Scale SQUID-On-Lever Scanning Probe
Marcus Wyss, K. Bagani, Daniel Jetter, Estefani Marchiori, Andriani Vervelaki, B. Gross, Joost Ridderbos, Sebastian Gliga, Christian Schönenberger, Martino Poggio
Abstract
Scanning superconducting quantum interference device (SQUID) microscopy is a magnetic imaging technique combining high field sensitivity with nanometer-scale spatial resolution. Here, we demonstrate a scanning probe that combines the magnetic and thermal imaging provided by an on-tip SQUID with the tip-sample distance control and topographic contrast of a noncontact atomic force microscope (AFM). We pattern the nanometer-scale SQUID, including its weak-link Josephson junctions, via focused-ion-beam milling at the apex of a cantilever coated with Nb, yielding a sensor with an effective diameter of 365 nm, field sensitivity of $9.5\phantom{\rule{0.2em}{0ex}}\mathrm{nT}/\sqrt{\mathrm{Hz}}$, and thermal sensitivity of $620\phantom{\rule{0.2em}{0ex}}\mathrm{nK}/\sqrt{\mathrm{Hz}}$, operating in magnetic fields up to 1.0 T. The resulting SQUID-on-lever probe is a robust AFM-like scanning probe that expands the reach of sensitive nanometer-scale magnetic and thermal imaging beyond what is currently possible.