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Diwen wuli xuebao

EFFECT OF WEAKLY INTERACTING ON ATOMS GAIN AND VALIDITY OF POTENTIAL FIELD FOR ATOM LASER

Qingrong Feng

Published Jan 1, 2011• 0 citations
OpenAlex

Abstract

We report a new sol-gel method for fabricating MgB2 films.Polycrystalline MgB2 films were prepared by spin-coating precursor solution of Mg(BH4)2 diethyl ether on (001)Al2O3 substrates followed with annealing in Mg vapor.In comparison with the MgB2 films grown by other techniques,our films show medium qualities including the superconducting transition temperature of TC~37K,critical current density of Jc (5 K,0T)~5×106 A/cm2,and critical field of HC2(0)~19T.This sol-gel technique has demonstrated to be potential in commercial fabrication of practical used MgB2 films as well as MgB2wires and tapes.

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Physica Scripta•Nov 24, 2025•0 citations
We report a new sol-gel method for fabricating MgB2 films.Polycrystalline MgB2 films were prepared by spin-coating precursor solution of Mg(BH4)2 diethyl ether on (001)Al2O3 substrates followed with annealing in Mg vapor.In comparison with the MgB2 films grown by other techniques,our films show medium qualities including the superconducting transition temperature of TC~37K,critical current density of Jc (5 K,0T)~5×106 A/cm2,and critical field of HC2(0)~19T.This sol-gel technique has demonstrated to be potential in commercial fabrication of practical used MgB2 films as well as MgB2wires and tapes.
We investigated full-epitaxial TiN/AlN/TiN Josephson junctions on MgO substrates for superconducting qubit applications. The critical temperature (TC) of TiN film is relatively low at around 5 K, but its lattice constant is about 0.424 nm, which is close to the lattice constant of MgO of 0.421 nm. TiN and AIN films were prepared by DC magnetron sputtering in a load-lock sputtering system with an ultra-high vacuum chamber. The deposition temperature was varied from ambient temperature to 1073 K. In XRD analysis, (200) peaks were observed in both the TiN single layer film and the TiN/AIN/TiN trilayer film. No other XRD peaks were observed in the single layer or trilayer films. The lattice constant of TiN was determined to be 0.4242 nm from XRD analysis, close to the value of 0.4212 nm for MgO. The 150 nm-thick single-layer TiN film on the MgO substrate showed a TCof 5.3 K and a resistivity of 3.5 μΩcm at 10 K. Based on these epitaxial TiN films, we fabricated TiN/AIN/TiN Josephson junctions and measured their current-voltage characteristics. At 1.9 K, the electrical parameters of junctions with JC= 50 A/cm2showed that the gap voltage and the ratio of Rsg/RNwere about 2.5 mV and 2.1, respectively.
A15 superconductors are distinguished by their high critical temperatures, magnetic fields, and current-carrying capabilities. Among them, Nb3_33​Al is of particular interest for superconducting quantum circuits as a means to extend device operating temperatures, provided that its electrodynamic properties are well understood. Here, we report on the synthesis of Nb3_33​Al thin films by magnetron co-sputtering followed by rapid thermal processing, yielding superconducting transition temperatures above 16~K. Microwire devices patterned from these films exhibit a coherence length of 3.2 nm3.2\,\mathrm{nm}3.2nm and superfluid densities as low as 1.1×1026 m−31.1\times 10^{26}\,\mathrm{m}^{-3}1.1×1026m−3, suggesting that Nb3_33​Al may enable high kinetic inductance in thinner films. Coplanar waveguide resonators fabricated on Nb3_33​Al demonstrate single-photon internal quality factors up to 2.26×1052.26\times 10^{5}2.26×105. These results establish Nb3_33​Al as a promising material platform for the development of superconducting quantum circuits operating at elevated temperatures, contingent on appropriate control of interfacial chemistry and surface morphology.
The physics of the interaction between coherent light and superconductivity is a very intriguing subject but the alignment of a laser beam with integrated superconducting systems (thin films, striplines or tunnel junctions) has represented so far a real bottleneck for the experimentalists. The integration of both junctions and waveguides on the same chip surely represents a possible path around this difficulty. In this paper we report on the combined integration of optical structures based on hybrid channel waveguides with superconducting Josephson junctions circuits. The optical films are grown on silicon substrates by a spin-coating process using the hybrid organic/inorganic sol–gel route. The channel waveguides are deposited on a buffer layer and realized by photolithographic and ion milling techniques. We find that the optical buffer is a good substrate for SIS Josephson junctions and circuitry based on the Nb/Al–AlO x / Nb trilayer processing. The junctions produced present good current–voltage characteristics with critical current density of the order of 1 kA cm −2 , high subgap resistance and good uniformity. Our results show that the quality of the Josephson junctions is well preserved even when they are grown on the sol–gel buffer layer.
Abstract In this report, we present the superconducting properties of NbTiN films grown by reactive DC magnetron sputtering on MgO substrates. The films were deposited at room temperature, 300 °C, and 600 o C to study the effect of deposition temperature on crystalline structure and superconducting behavior. Superconducting parameters such as transition temperature (T c ), coherence length ( ξ (0)), and upper critical field (B C2 (0)) were obtained from resistance–temperature measurements. A clear dependence of structural and superconducting properties on deposition temperature was observed. Resistance–temperature data were analyzed using Aslamazov–Larkin (AL) and Lowest Landau Level (LLL) scaling theories to describe the superconducting fluctuation mechanism. Magnetoconductance curves extracted from magnetoresistance (MR) measurements were analyzed within the AL + MT fluctuation framework to estimate the dephasing time ( τ ϕ ) in the picosecond range. All these findings are crucial for understanding the response and recovery time of superconducting single-photon detectors. The successful growth and robust parameters of high-temperature-deposited NbTiN films indicate their potential for superconducting photon detectors, kinetic inductance detectors, and other quantum applications.