The scanning superconducting quantum interference device (SQUID) fabricated on the tip of a sharp quartz pipette (SQUID-on-tip) has emerged as a versatile tool for nanoscale imaging of magnetic, thermal, and transport properties of microscopic devices of quantum materials. We present the design and performance of a scanning SQUID-on-tip microscope in a top-loading probe of a cryogen-free dilution refrigerator. The microscope is enclosed in a custom-made vacuum-tight cell mounted at the bottom of the probe and is suspended by springs to suppress vibrations caused by the pulse tube cryocooler. Two capillaries allow in-situ control of helium exchange gas pressure in the cell that is required for thermal imaging. A nanoscale heater is used to create local temperature gradients in the sample, which enables quantitative characterization of the relative vibrations between the tip and the sample. The spectrum of the vibrations shows distinct resonant peaks with maximal power density of about 27 nm/Hz1/2 in the in-plane direction. The performance of the SQUID-on-tip microscope is demonstrated by magnetic imaging of the MnBi2Te4 magnetic topological insulator, magnetization and current distribution imaging in a SrRuO3 ferromagnetic oxide thin film, and by thermal imaging of dissipation in graphene.
@article{arxiv.2304.11667,
title = {Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator},
author = {Haibiao Zhou and Nadav Auerbach and Indranil Roy and Matan Bocarsly and Martin E. Huber and Barun Barick and Arnab Pariari and Markus Hücker and Zhi Shiuh Lim and A. Ariando and Alexey I. Berdyugin and Na Xin and Michael Rappaport and Yuri Myasoedov and Eli Zeldov},
journal= {arXiv preprint arXiv:2304.11667},
year = {2023}
}