Magnetic resonance imaging of the nanoscale resolution will be a powerful non-destructive probing tool to for the Biology and Material Science. As the imaging voxel shrinks into the nanoscale, the number of spins that can generate a resonance signal become very small. Fortunatly, the SQUID miniaturized into nanoscale is promising in the inductive detection of a single electron spin. Therefore, A nano-SQUID with a strong spin coupling coefficient, a low flux noise, and a wide working magnetic field range is highly desired in a single spin resonance measurement. The nano-SQUID with Dayem-bridge junctions are excel in a high working field range and a direct coupling from spins to the bridge. However, the common planar structure of nano-SQUID is known for problems such as a shallow flux modulation depth and a readout-troublesome hysteresis in the current-voltage curves. Here, we developed a fabrication process for a 3D Nb nano-SQUIDs with nano-bridge junctions. The characterization of the device shows a up to 45.9% modulation depth with a reversible current-voltage curve. Owning to the large modulation depth, the measured flux noise is as low as 0.34 μΦ0/Hz1/2. The working field range of the SQUID is more than 0.5 T. We believe that the 3D Nb nano-SQUIDs provides a promising step towards the single-spin inductive detection.
The speaker graduated from the Department of Physics, Fudan University in 2003, and got his PhD from the Department of Physics, Florida State University in 2010. During his PhD, he developed an on-chip SQUID measurement system at the high magnetic field (7 Tesla) and at the ultra-low temperature (5 mK), and studied the quantum tunneling effect of the single molecular magnets. From 2011 to 2013, he joined the department of Chemistry and Chemical Biology as an post-doc researcher and developed an magnetic resonance force microscope for studying the microscopic mechanism of the dynamic nuclear polarization. In 2013, he joined the SIMIT as an associate professor to carry out research work on the nano-SQUIDs and the related applications.
邀请人:刘荧 yingl@sjtu.edu.cn