Improved techniques for measurement of superconductivity in diamond anvil cells by magnetic susceptibility

Recent improvements in magnetic inductive measurements of superconductivity over a broad range of pressures in high-pressure diamond anvils cells are described. A significant increase in sensitivity is obtained by the application of resonant circuits with voltage increasing transformers, allowing an increase in the working frequency of the experimental setup. As a result, superconductivity in samples with linear dimensions as small as 10 mum can be detected. Recent results obtained with this resonant circuit on samples of sulfur at 230 GPa are presented. Further increase in the sensitivity of the experimental setup can be obtained by summing the results of repeated measurements obtained in the same temperature interval. An example is provided by measurements on a small sample of lead. (C) 2002 American Institute of Physics.