Harmonic generation studies in laser ablated YBCO thin film grown on 〈100〉 MgO

Generation of even harmonics in a MgB2bulk superconductor: an indication of the presence of weak link grain boundaries

“…(a) In MgB 2 , the application of a dc field (∼few gauss) along with the ac field results in the generation of a second harmonic and very small magnitude of fourth harmonics, whereas in polycrystalline high-T c superconductor generation of second, fourth, sixth and tenth harmonics are observed. (b) In bulk high-T c YBCO, the amplitudes of even and odd harmonics have been found to modulate with the variation of H dc showing maxima and minima [11], whereas in The observed features of harmonic generation in the MgB 2 polycrystalline bulk is more similar to that observed in YBCO thin film deposited on MgO(100) using the laser ablation technique [12]. In this YBCO film most of the grain boundaries are clean type with high critical current densities (J c ) and a few grain boundaries are the weak link type.…”