Effects of weak magnetic fields on post-implantation damage in superconducting oxides

Abstract

Experimentally verifiable effects of weak permanent magnetic fields (PMF’s) acting during ion implantation in high-Tc superconducting (HTSC) materials at T ⋍ 300K on post-implantation damage (PID) and material parameters are considered. The presence of PMF’s of H ⋍ 103Oe during ion implantation can enlarge substantially the PID in HTSC materials implanted with ions of moderate energies (e.g. 200–400 keV) and dosage (1011-1012 cm-3) at room temperature. The PMF-induced increase in the radiation damage causes the corresponding enhancement in the material resistivity R and reduction in the critical current jcir (measured after the cooling of the HTSC material down to T(L) < Tc after the ion implantation). This is an extension of the PMF effects found experimentally (and explained theoretically) in semiconductors in our previous work [7]. The experimentally verifiable PMF effects on the defect (atomic) migration and radiation damage is a generic consequence of the kinetic electron-related theory of atomic rate processes in solids. The theory links the PMF effects with electron transitions occurring in the nanometer vicinity of atoms overcoming energy barriers which affect exponentially rates of atomic (defect) diffusion. The magnetic field can enhance the number of downward electron transitions that accompany atomic (defect) jumps over energy barriers and synchronize with the jumps. This enhances exponentially the rates of defect migration out of thermal spikes that prevents the defects from fast recombination, and thus, the PMF increases the PID and changes correspondingly R and jcir.