Grain Boundary Induced Magneto-Far Infrared Resonances in Superconducting YBa${}_2$Cu${}_3$O${}_{7-\delta }$ Thin Films

Abstract

Spectral features induced by 45${}^{\circ }$ in-plane misoriented grains have been observed in the far infrared magneto-transmission of YBa${}_2$Cu${}_3$O thin films. Two strong dispersive features are found at 80 and 160 $c{m}^{-1}$ and a weaker one at 116 $c{m}^{-1}$. The data can be well represented by Lorentzian oscillator contributions to the conductivity. Several possible interpretations are discussed. We conclude that the resonances are due to vortex core excitations.

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