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Local tunneling characteristics near a grain boundary of a d-wave superconductor as probed by a normal-metal or a low-Tc-superconductor STM tipZhao, Hongwei 29 August 2005 (has links)
We studied the local single-particle tunneling characteristics [as observed with scanning
tunnel microscopy (STM)] for N D and S D tunneling, where N is a normal
metal, S is a s-wave superconductor, and D is a d-wave superconductor with
a {100} | {110} grain boundary. The tunneling Hamiltonian method was used. The
self-consistent order parameter is first determined using the quasiclassical Green'sfunction
method, and then the tunneling characteristics at various distances from
the interface, reectivity of the interface, and temperature are studied. For N D
tunneling, a zero-bias conductance peak (ZBCP) occurs near the interface with diminishing
magnitude away from it. For S D tunneling, the ZBCP splits to exhibit
the gap of the s-wave low-Tc superconducting tunneling tip and there is a range of
negative conductance just outside the peaks when the tunneling point is near the
grain boundary. The results are compared with those obtained by using a constant
order parameter in each grain.
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