Research On Superconducting Quantum Properties And Basic Experiments

Since the discovery of the Josephson effect in the 1960s,the superconducting quantum interference device(SQUID)based on the Josephson effect has been widely concerned for its excellent magnetic measurement performance.Due to technical limitations,the early manufacturing methods of SQUID devices were mainly point contact methods.However,with the development of thin film technology,thin film SQUID devices have become the main manufacturing technology.At present,the preparation of SQUID based on low-temperature materials in the laboratory is very mature,but there are still great problems in practical applications.In this thesis,for the purpose of studying the superconducting quantum effect,a series of experiments on the preparation of SQUID were carried out.The basis for making thin film SQUID is to make superconducting thin films.We choose niobium nitride as the coating material.First,niobium nitride has a higher superconducting critical temperature in low-temperature superconducting materials.Second,we choose magnetron sputtering as the coating method.The operation for preparing niobium nitride thin films is relatively simple.In the experiment,we compared the effects of different nitrogen flow rates and substrate temperature on the film formation effect of the niobium nitride film.The experiments proved that the temperature has a great effect on the film formation effect,and different nitrogen flow rates also have a significant effect on the film formation effect.In order to measure the experimental signals,we have made two measurement systems.One set is a board made with C8051F350 single-chip microcomputer as the core.This system has 24-bit high-precision AD conversion.Even if certain errors are removed,the microvolt level can be measured,but the conversion rate is relatively slow.The board made for the core can be converted very quickly,but because the number of AD bits is low,the signal must be amplified by the amplifier circuit before it can be input into the microcontroller,so the actual measurement range will be greatly limited.After the actual measurement,Both systems can achieve the desired results.Two different methods were used to make the Josephson junction in the experiment.The Josephson junction in the form of point contact is greatly affected by the vibration of the refrigerator.The junction is easy to conduct and completely separate.The success rate is very low.Experimental parameters require more experiments to explore.This paper has designed two different ways to make SQUID devices,and the specific effects have yet to be experimentally verified.