Magnetic Properties of High-T sub c YBa sub 2 Cu sub 3 Length Scales
20 March 1989
An electrodynamic force balance has been constructed in which the perturbative forces from applied magnetic field H are used to probe the superconducting properties of single levitated charged grains of high-T sub c superconductors with diameters ~10microns. A resolution of 10 sup -4 of the gravitational force on the particle has been obtained, and individual particles have been recovered for microscopic characterization. Results of measurements of T sub c, the lower critical field H sub c1, the Meissner effect, flux trapping, and time- dependent magnetization of YBa sub 2 Cu sub 3 O sub 7 particles will be reported. This instrument provides a unique capability to measure the magnetic properties of particles which have a size approximately a factor of 100 below the scale constraints imposed by conventional measuring instruments.