Scanning SQUID Platform

quantitative microscale magnetic imaging


A scanning-SQUID microscope is an ultra-sensitive system for quantitative measurement of weak local magnetic fields on the microscale. The probe consists of a superconducting quantum interference device (SQUID), which is scanned several hundreds of nanometers above the sample surface.

The biggest advantage of sSQUIDs over other magnetic scanning probe techniques is its unmatched magnetic field sensitivity down to the nT range [1]. The drawback on the other hand is the limited spatial resolution of usually above 1 µm only, although there are some promising new approaches with much higher spatial resolution [2].

Collaborating with the group of K. Moler & J. Kirtley (Stanford, USA), attocube has designed a platform for cryogenic sSQUID, based on the attoSHPM. The microscope includes all necessary scanner, positioners, cabling, electronics and a sensor head with an adjustable tilt stage for the sensor, but no SQUID sensor or SQUID electronics.

It provides a low temperature lateral scan range of 125 μm, which can optionally be equipped with encoders for closed loop operation and fully linearized scans.

If needed, a specially adapted microscope configuration allows for large temperature gradients of up to 100 K (liquid cryostat) between SQUID sensor (kept at less than 7 K) and the sample [3].

This allows to study temperature dependent effects and samples with high transition temperatures despite using a sensitive superconducting device.

[1] M. Zech et al., Microscopy Today 19 (06), 34-38 (2011)
[2] A. Finkler et al., Rev. Sci. Inst. 83, 073702 (2012)
[3] B. Kalisky et al., Nature Materials 12, 1091 (2013)

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