We have fabricated high-T(c) nanoscale superconducting quantum interference devices (nanoSQUIDs) with a hole size of 250 nm × 250 nm based on a 100 nm bridge at 77 K by focused ion beam milling and ion implantation. At 78 K, the curve of the voltage branch became roughly linear and agreed with the Josephson-like behavior. The sample exhibited strong flux flow behavior at temperatures under 76 K. The voltage flux characteristic curves, V -I(mod), of the nanoSQUID at different bias currents at 78 K were observed. Typically, critical currents of 15 µA and peak-to-peak values of the voltage flux transfer function of 3.7 µV were measured. The measured data strongly suggest that the weak link structure could be a superconducting metal with a critical temperature T(c)' smaller than that (T(c)) of other YBa(2)Cu(3)O(7-x) (YBCO) films. This fabrication method of combining a nanobridge and ion implantation can improve the yield of nanojunctions and nanoSQUIDs.

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We have successfully fabricated YBCO Josephson junctions and SQUIDs with variable thickness bridges. The variable-thickness bridges of YBCO thin film were fabricated by photolithography and Focused ion beam mill. The Josephson effects of variable thickness bridges were obtained in a 80 nm-thick-film of high-c YBa 2 Cu 3 O y . The Shapiro steps were observed in single junction in the gigahertz range from 3.02 to 14.64 GHz. The voltage-current and voltage-field characteristics were measured in SQUID magnetometer. The SQUID shows a peak-to-peak voltage swing of 1.5 V at 70 K. The properties of one junction and SQUID magnetometer have been investigated. Index Terms-Focused ion beam, Josephson junction, variable thickness bridges.

Ag2S@TiO2 films was made as humidity sensors by SILAR method. The heterojunction and nano-silver improve the electrons transfer and increase the response and reaction rate. It also provides high gas selectivity to avoid effect of air pollution.

We have designed four multifunctional high-transition-temperature directly-coupled superconducting-quantum-interference-device (SQUID) magnetometers on a 10 mm × 10 mm SrTiO 3 bicrystal substrate. Each magnetometer is composed of two serial bare SQUIDs. These magnetometers can be connected to four kinds of first-order electronic planar gradiometers or two kinds of second-order electronic planar gradiometers by using analog subtracting electronic circuits. The performance and noise spectra of each magnetometer, two first-order electronic planar gradiometers and a second-order planar gradiometer were measured. We measured the small magnetic signal generated from a double D coil to show that this design could supplement the deficiency of a magnetometer.A superconducting quantum interference device (SQUID) magnetometer is the most sensitive magnetic sensor in the world. It has been widely applied in many different territories, such as solid state physics, biology, geography, astronomy 1 , etc. After the discovery of high-transition temperature superconducting (HTS) material, many HTS SQUID systems have been constructed and applied to different applications such as nondestructive evaluation (NDE), scanning SQUID microscope (SSM), and magnetocardiography (MCG) 1 , etc. For practical applications, a multi-channel system 2-3 is more useful and powerful, especially in bio-magnetic research. A multi-channel system could perform a large area measurement and reduce measuring time. Alternatively, a multi-channel system offers the possibility for the measurement of the gradient of magnetic field.Referring to the concept of a multi-channel system, we have developed a multi-functional design of HTS dc SQUID magnetometers on a chip to increase the flexibility of applications. In our design, four dc SQUID magnetometers are fabricated on a 10 mm × 10 mm SrTiO 3 bicrystal substrate. Each magnetometer is composed of two serial bare SQUIDs, with 3 μm wide Josephson junctions, and of a 4 mm × 4 mm pick up loop with a width of 200 μm. As a result, we are able to create at most four magnetometers in one fabricating process. Though it is unlikely that the performances of each magnetometer will be the same, we can choose the best one for practical applications.Furthermore, these four magnetometers can be used to construct four kinds of first-order electronic planar gradiometers or two kinds of second-order electronic planar gradiometers by using analog subtracting electronic circuits. Hence, the magnetic field, B z , the first-order spatial derivatives of the magnetic field, ∂B z /∂x and ∂B z /∂y, and the second-order spatial derivative of the magnetic field, ∂ 2 B z /∂x∂y and ∂ 2 B z /∂y∂x, can be measured at the same time. For those applications working in unshielded environment, reducing the influence from the external noise is very important. Gradiometers have been shown to reduce the noise from the external environment 4 . We will show that the electronic planar gradiometer based on our design could work well under the unshielded env...