Observation of vortex pinning in YNi2B2C by LT-STS

The scanning tunneling spectroscopy measurements have been performed on the cut or cracked surface of YNi2B2C at 4.2 K in magnetic fields. The map of the quasiparticle density of states at the Fermi energy has revealed the vortex cores and the semiconducting precipitates. When the applied magnetic field is increased at 4.2 K, the enhancement of the local density of states has been observed along the boundary of the semiconducting precipitate. This enhancement is attributed to a number of pinned vortices at the boundary