Magnetic Responses of Zero-bias Conductance Peaks by LT-STM

In order to elucidate the surface electronic structure of oxide superconductors, low-temperature scanning tunneling microscopy/spectroscopy has been applied to observe YBCO film surfaces. Some of the conductance spectra obtained in the absence of magnetic field showed zero-bias peaks with linear backgrounds. The responses of the zero-bias conductance peaks to the applied magnetic field were consistent with the Appelbaum-Anderson tunneling model. This indicates that localized spins exist on the YBCO surface. The linear conductance background is discussed in terms of inelastic scatter at the anti-ferromagnetic surface layer.