NanoSQUIDs for the study of quantum spin dynamics

Superconducting Quantum Interference Devices (SQUIDs) are among the most sensitive magnetic sensors in the solid state. QMAD develops and exploits micro- and nano-SQUID sensors to perform a wide variety of magnetization measurements at low temperatures, reaching extremely large sensitivities and broadband frequency operation. 

This is possible thanks to the use of Nb-based SQUID microsusceptometers and YBCO-based nanoSQUID magnetometers. The latter also allow the application of extremely large sweeping magnetic fields (Tesla range) and high temperatures (below 80 K). 

Based on these capabilities, we study dynamical quantum effects in spin-qubits, e.g., single atom magnets, or magnetization dynamics in topological magnetic states, e.g., vortices and domain walls, at very low temperatures. Our future plans include the implementation of magnetization measurements with picosecond time-resolution and the development of a scanning nanoSQUID microscope.

Nb SQUID microsusceptometers:
Sensitivity: 102 mB/Hz1/2
Temperature range: mK – 5 K
Magnetic field: < 5 G (AC)
Frequency bandwidth: mHz – 1 MHz

In collaboration with:

University of Tübingen


YBCO nanoSQUID magnetometers:
Sensitivity: 5  mB/Hz1/2
Temperature range: mK – 80 K
Magnetic field: < 1 T (DC)
Frequency bandwidth: mHz – 20 MHz