# MicroSQUID Force microscopy in a dilution refrigerator

1 NEEL - Institut Néel 2 beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science 3 Nanofab - Nanofab NEEL - Institut Néel 4 MagSup - Magnétisme et Supraconductivité NEEL - Institut Néel 5 IRAM - Institut de RadioAstronomie Millimétrique

Abstract : We present a new generation of a scanning MicroSQUID microscope operating in an inverted dilution refrigerator. The MicroSQUIDs have a size of 1.21$\ \mu$m\textsuperscript{2} and a magnetic flux sensitivity of 120 $\mu\Phi {0} - \sqrt{\textrm{Hz}}$ and thus a field sensitivity of %$550^{-6} \ \Phi {0} - \sqrt{\textrm{Hz}}$ 550$\ \mu \textrm{G}- \sqrt{\textrm{Hz}}$. The scan range at low temperatures is about 80 $\mu$m and a coarse displacement of 5 mm in x and y direction has been implemented. The MicroSQUID-to-sample distance is regulated using a tuning fork based force detection. A MicroSQUID-to-sample distance of 420 nm has been obtained. The reliable knowledge of this distance is necessary to obtain a trustworthy estimate of the absolute value of the superconducting penetration depth. An outlook will be given on the ongoing direction of development.

keyword : Superconductivity Scanning Microscopy SQUID

Author: Danny Hykel - Zhao-Sheng Wang - Pauline Castellazzi - Thierry Crozes - Gorky Shaw - Klaus Hasselbach - K. F. Schuster -

Source: https://hal.archives-ouvertes.fr/