Single Bohr Mangeton Detector
Abstract
We have successfully developed a superconducting quantum interference device magnetometer employing nanoscale weak links (nanoSQUIDs) with a dispersive microwave readout. These sensors have a flux sensitivity of 25 nano01/Hzl/2, which translates into single Bohr magneton resolution (for a 1 Hz bandwidth) for magnets placed within 100 nm of the sensor-a very reasonable task for current e-beam and scanned probe lithography. In our nanoSQUID magnetometer, the SQUID is incorporated into a 5 GHz microwave tank circuit. The magnetization of a spin signal under study shifts the resonant frequency of the resonator which is readily detected using microwave reflectometry. The weak links are made of aluminum and have been optimized for maximum nonlinearity by contacting the narrow (25-50nm), thin ( 6nm) bridge with think (>50nm) contacts, which serve as good phase reservoirs. The measured current phase relation and inductance modulation is in excellent agreement with our numerical simulations based on a solution of the Usadel equations. Both our observed the flux sensitivity and instantaneous bandwidth of~ 10-40 MHz are several orders of magnitude higher than other types of nanoSQUID sensors currently reported in the literature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 09, 2011
- Accession Number
- ADA563668
Entities
People
- Irfan Siddiqi
Organizations
- University of California, Berkeley