Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator.

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 the 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.

Three-junction SQUID-on-tip with tunable in-plane and out-of-plane magnetic field sensitivity.

Nanoscale superconducting quantum interference devices (SQUIDs) demonstrate record sensitivities to small magnetic moments but are typically sensitive only to the field component that is normal to the plane of the SQUID and out-of-plane with respect to the scanned surface. We report on a nanoscale three-junction Pb SQUID, which is fabricated on the apex of a sharp tip. Because of its three-dimensional structure, it exhibits a unique tunable sensitivity to both in-plane and out-of-plane fields.

A scanning superconducting quantum interference device with single electron spin sensitivity.

Superconducting quantum interference devices (SQUIDs) can be used to detect weak magnetic fields and have traditionally been the most sensitive magnetometers available. However, because of their relatively large effective size (on the order of 1 µm), the devices have so far been unable to achieve the level of sensitivity required to detect the field generated by the spin magnetic moment (μB) of a single electron. Here we show that nanoscale SQUIDs with diameters as small as 46 nm can be fabricated on the apex of a sharp tip.

Lifetime measurements in an electrostatic ion beam trap using image charge monitoring.

A technique for mass-selective lifetime measurements of keV ions in a linear electrostatic ion beam trap is presented. The technique is based on bunching the ions using a weak RF potential and non-destructive ion detection by a pick-up electrode. This method has no mass-limitation, possesses the advantage of inherent mass-selectivity, and offers a possibility of measuring simultaneously the lifetimes of different ion species with no need for prior mass-selection.

Self-aligned nanoscale SQUID on a tip.

A nanometer-sized superconducting quantum interference device (nanoSQUID) is fabricated on the apex of a sharp quartz tip and integrated into a scanning SQUID microscope. A simple self-aligned fabrication method results in nanoSQUIDs with diameters down to 100 nm with no lithographic processing. An aluminum nanoSQUID with an effective area of 0.

Fragmentation channels in dissociative electron recombination with hydronium and other astrophysically important species.

We report on our recent studies of dissociative recombination (DR) employing two different fragment imaging detection techniques at the TSR storage ring in Heidelberg, Germany. Principles of an upgraded 3D optical system and the new energy-sensitive multistrip detector (EMU) are explained together with possible applications in reaction dynamics studies. With the EMU imaging detector we succeeded to observe the branching ratios after DR of deuterated hydronium ions D(3)O(+) at energies of 0-0.