  We have studied the evolution of the Zero-Bias Conductance Peak (ZBCP)
splitting under applied magnetic fields in tunneling experiments on
Y1Ba2Cu3O7-x(YBCO), and particular its hysteresis. We have been able to
distinguish between two possible contributions to the splitting. One of them is
connected to Meissner screening currents whose variation in increasing fields
is governed by the Bean-Livingston barrier that delays flux entry well above
the lower thermodynamical critical field Hc1, up to the fields of the order of
the thermodynamical critical field Hc. The other contribution, dominant in
(110) oriented films, is seen in decreasing fields where there are no Meissner
screening currents, since there is no barrier to flux exit and it may be
connected to the magnetic induction in the sample as proposed by Laughlin.
