Transition Temperature Superconducting Quantum Interference Research Articles

Measurement of Magnetic Nanoparticles Using High Transition Temperature Superconducting Quantum Interference Devices

Superconducting quantum interference device (SQUID) based sensors hold promise for magnetic detection of magnetically tagged biological cells. In this work, a high transition temperature (high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> ) direct-coupled SQUID micro-magnetometer was fabricated from a 30-nm-thick YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> (YBCO) thin film. The SQUID was directly written with irradiation from a finely focused helium ion beam without milling or etching any material. An experiment estimating the sensitivity of the magnetometer to magnetic nanoparticles was conducted that revealed the magnetic moment calculated based on the measurement of the SQUID magnetometer is consistent to that obtained from susceptibility measurements.

Characterization of dual high transition temperature superconducting quantum interference device first-order planar gradiometers on a chip

The dual first-order planar gradiometers of high transition temperature (high-Tc) superconducting quantum interference devices (SQUIDs) were designed and fabricated on a 10×10 mm2 SrTiO3 bicrystal substrate. Each gradiometer consists of four bare SQUIDs which are connected to two symmetric pickup loops. Any two of the SQUIDs can be connected in series to obtain better performance. In this study, by selecting the coupling direction of SQUID, a balance resolution of 0.08% was achieved. And, a second-order electronic planar gradiometer was composed of these two first-order gradiometers. Experimental data showed that the noise performance of the second-order electronic planar gradiometer composed of two planar first-order gradiometers can reach 15 μΦ0/Hz1/2 at 1 kHz in an unshielded environment, which is comparable to the noise level of a magnetometer in a shielded environment.

Tunable high transition temperature superconducting quantum interference device magnetometer with gate-voltage-controlled bicrystal junctions

A gate-voltage-controlled high transition temperature direct current superconducting quantum interference device (high-Tc dc SQUID) magnetometer was fabricated to study how the electric field effect affects the device’s voltage-flux and voltage-current characteristics. The magnetometer consists of a monolithic YBa2Cu3O7−δ superconducting film and bicrystal junctions covered by a polymethylmethacrylate film as the gate insulator. It was found that the magnetic flux modulated voltage swing of the SQUID magnetometer varies by 48% when the gate voltage is changed from −1.9 to 9.5 V. The variation in voltage swing is attributed to the change of effective capacitance in grain-boundary junctions.

High Transition Temperature Superconducting Quantum Interference Devices: Basic Concepts, Fabrication and Applications

The performance of superconducting quantum interference devices (SQUIDs) and SQUID based magnetometers made from thin films of high transition temperature superconductors (HTS) has greatly improved since the discovery of HTS more than a decade ago. This fact is related to a steady improvement in the fabrication technology for HTS thin films and Josephson junctions. The state-of-the-art in HTS SQUID fabrication, device concepts and applications is briefly reviewed.

Low field magnetic resonance images of polarized noble gases obtained with a dc superconducting quantum interference device

Using a low transition temperature superconducting quantum interference device as a detector, we have obtained magnetic resonance images of laser-polarized He3 gas and solid Xe129 at 4.2 K in magnetic fields as low as 0.54 mT (3He) and 1 mT (129Xe), corresponding to Larmor frequencies of 17.6 and 11.8 kHz, respectively. The experimental resolution of the images is ∼500 μm for He3 in the gas phase and ∼950 μm for Xe129 in the solid state.