Modulation of Kinetic Inductance of High Tc Superconducting Thin Films with Bias Current

Kinetic inductance of high T c superconducting thin films is studied using numerical simulation of the Ginzburg-Landau (GL) theory. It is shown that a current distribution in the film changes nonlinearly with a bias current supplied to the film, which results from the nonlinear properties of the GL equation. Using the current distribution, the kinetic inductance of the film is obtained as a function of the bias current. It is shown that the kinetic inductance is constant for low bias currents, and increases nonlinearly with the bias current when the bias current becomes large. The effect of the film geometry on the modulation of the kinetic inductance is quantitatively studied. Analytical solutions for the current distrubiton and the kinetic inductance are also obtained, which agree well with the simulation results. The modulation of the kinetic inductance with the bias current predicted from the theory is partly confirmed from experiments using YBaCuO films.