Ultrasensitive nanoSQUIDs for the detection of small spin systems

01/03/2014 to 28/02/2017

In this research project we shall realize and investigate a new kind of submicron-sized superconducting quantum interference devices (nanoSQUIDs). Those devices shall be able to directly detect the magnetic dipole field of small magnetic systems with magnetic moments on the order of a few Bohr Magnetons. For optimum spin sensitivity the SQUIDs have to be optimized with respect to their flux sensitivity and the magnetic coupling at the same time. In comparison to previous works, the proposed trilayer Josephson junction technology based on Nb-HfTi-Nb or Nb-NbSi-Nb offers much more flexibility to optimize both terms. In addition the high critical current density of those junctions will allow for nano-sized junctions which is necessary for operation in large external magnetic fields. The nanoSQUIDs based on the proposed materials shall be designed to operate in magnetic fields up to several 100 mT and in a temperature range from 5 K down to below 100 mK. This will allow for applications like scanning SQUID microscopy or magnetization measurements of nano-particles or the detection of Bose-Einstein condensates of cold atom clouds.