Research Of Electric Transport Measurement In Pulsed High Magnetic Field

The systems of electric transport measurement, based on DC current implementation and AC one, in pulsed high magnetic field have been studied. The study includes temperature controlling, field measurement and electric transport measurement. Meanwhile, the electric transport behaviors of La0.5Ca0.5MnO3 have also been investigated under the DC system. And the results show that this system can be successfully used for studying transport properties of magnetic materials in pulsed high magnetic field, but there is much noise for weak signals. Finally, a detailed analysis on AC system has been given. The main points of this paper are as following:Firstly, an overview of the development of pulsed high magnetic field is given, and some applications in materials science are introduced. The facilities of electric transport measurement in the Pulsed Magnetic Field Center of HuaZhong University of Science & Technology, that is the experiment platform of our study, have been simply described. Particularly, many suggestions on improving the signal to noise ratio have been given.Secondly, the theory and the characteristics of measurement of electric transport system in pulsed high magnetic field laboratories are described. The hardware including the sample holder, signal pick-up, process and the temperature controlling system were described.Thirdly, the magnetic field measured by electromagnetism induction method with pick-up coils and various calibrations of the area of the pick-up coils have been discussed. The uncertainty of the magnetic field intensity is only 0.4% between two pulses with the same discharge voltage.Fourthly, the system for measuring DC electric transport has been introduced. Based on this system, the DC electric transport properties of La0.5Ca0.5MnO3 have been measured. The first-order transition and insulator-metal transition in La0.5Ca0.5MnO3 bulk were observed. In addition, the suppression of current on charge ordering was also shown.Finally, the system for measuring AC electric transport has been introduced, especially on the lock-in amplifier.