Enhanced critical magnetic field in superconducting Pb nanoparticles

Pb nanoparticles in a powder form has been successfully fabricated by employing the gas condensation method. Analyses based on the x-ray diffraction profiles and the AFM images showing a mean particle size of 6 nm, with a relatively narrow size distribution of half-width 1.5 nm, for the powder. It is known that bulk Pb has a superconducting transition temperature of T_C=7.2 K and a critical magnetic field of H_C=803 gauss. Magnetic susceptibility and electrical resistance measurements show that T_C of the 6 nm Pb nanoparticles reduces to 6.6 K, which was found to be extremely insensitive to the applied magnetic field. Screening diamagnetic responses remains even at H_a=9 T with which T_C=6 K.