Nucleation of the Supercooled Normal to Superconducting Phase Transition in Small Indium Spheres Induced byγRadiation

Abstract

We have observed that low energy g rays nucleate the supercooled normal to superconducting phase transition in micron-sized indium spheres. The mechanism for the nucleation in the superconducting sphere may have similarities to some aspects of the "baked Alaska" model proposed by Leggett for liquid 3 He in which cosmic rays nucleate the transition from the supercooled superfluid A phase to the B phase. [S0031-9007(97)

Diamagnetic interactions in disordered suspensions of metastable superconducting granules

“…Applying the iterative method described above, the values of the coefficients c are obtained, which enables determination of the local values of the magnetic field on the surface of any sphere from Eqs. (1,4). The maximum value of the surface field for each sphere is then calculated by standard routines of minimization of multivariate functions.…”

“…For example, the measurement of the supercritical fields of disordered suspensions of superconducting granules has yielded determinations of the Ginzburg-Landau parameters of the superconducting transition 2 . On the other hand, the superheated-to-normal phase transitions of Type I superconducting suspensions, induced by irradiation, have served as the basis for the recent development of particle detectors 3 ; also the irradiation-induced supercooled normal-to-superconducting transition of granular arrays is being explored 4 with respect to dark matter detection in astroparticle physics. In a superconducting granular material, the transition of each granule is determined by its position in its phase diagram, which is schematically shown in Fig.…”