We have measured the field dependence of the zero-bias conductance peak (ZBCP) of tunnel junctions prepared on (110) oriented YBa2Cu3O7-δ films of various thickness. We have found that the field splitting of the ZBCP, believed to be due to the time reversal symmetry breaking (TRSB) of Andreev surface-bound states, is independent of film thickness. This rules out that Meissner screening currents are at the origin of TRSB. We conclude that TRSB must, instead, be due to a field-induced modification of the order parameter. Different possibilities involving an imaginary component are discussed.
|Number of pages||3|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Sep 2001|