Bean-Livingston barrier enhancement on nodal surface of the d-wave superconductor YBa2Cu3O{7-x}

Vortex entry into (110) oriented YBa${}_2$Cu${}_3$O${}_{7-x}$ films has been studied by tunneling into Andreev - Saint-James bound states, whose energy is shifted by surface currents. At low temperatures, the characteristic field for vortex entry has been found to increase up to values several times higher than that of the Bean-Livingston entry field for conventional superconductors, in agreement with recent theoretical predictions.