Influence of magnetic field on tunneling conductance in normal metal/dx2-y2-wave superconductor junctions

Influences of magnetic field on tunneling conductance spectra in normal metal/d(x2)-(y2) -wave superconductor junctions are studied on the basis of the quasiclassical Green's function method where the spatial dependence of the pair potential is determined self-consistently. Focuses are set on the field response of the zero-bias conductance peaks (ZBCP). For the detection of the splitting of the ZBCP due to broken time-reversal symmetry states, we found the presence of a critical value for the magnetic field strength in contrast to previous theories. The critical field H-C is almost proportional to the width of ZBCP in the absence of field and equivalently to the transparency of the junctions. The present result may explain the origin for the inconsistency of the magnetic field responses in several experiments.