Project Details
Projekt
Advanced nanoSQUIDs for the detection of small spin systems
Subject Area
Experimental Condensed Matter Physics
Term
from 2014 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 249226987
In this research project we shall develop and investigate advanced submicron-sized superconducting quantum interference devices (nanoSQUIDs). NanoSQUIDs are able to directly detect the magnetic dipole field of tiny magnetic systems such as magnetic nanoparticles (MNPs) or single molecular magnets with magnetic moment sensitivity down to the order of a Bohr magneton in a 1 Hz bandwidth. Despite considerable progress in the development of ultrasensitive nanoSQUIDs and appropriate measuring techniques, solutions still do not exist for real applications. To overcome this, we want to develop sensors and overall systems for real applications, with focus on nanoSQUID magnetometry and susceptometry on MNPs.Fabrication of the niobium (Nb) nanoSQUIDs will be based on a mature technology for realizing ultra-small, high critical current density Nb/HfTi/Nb Josephson junctions, instead of most frequently used Josephson junctions based on geometric constrictions. This offers the unique advantage of combining the realization of SQUIDs with very small loop inductance and hence extremely low flux noise, with a superconductor multilayer approach that offers the realization of complex devices with significantly increased functionality for various applications.Within the project we will address still unsolved issues on the basic properties of our Josephson junctions and nanoSQUIDs to further improve their performance, including operation in strong magnetic fields and over a large temperature range. Based on this, we intend to implement advanced dispersive readout schemes to avoid dissipation and achieve highest bandwidth and sensitivity. We will develop advanced nanoSQUID circuits, such as vector nanoSQUIDs, nanoSQUID susceptometers and current sensors. Those will be particularly suited for the investigation of MNPs, as a major application of nanoSQUIDs. In order to address a key challenge for this kind of application, we intend to develop a practical and reliable technique for positioning MNPs in close vicinity of our nanoSQUIDs. This shall also include the possibility to vary the temperature of the MNPs during measurement. Finally, we will perform proof-of-principle measurements on MNPs to demonstrate the success and feasibility of our approaches.
DFG Programme
Research Grants
