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摘要
We study the inhomogeneity of the pairing gap near the surface of Bi2Sr2CaCu2O8+delta due to interstitial oxygen dopants. Within the slave boson mean-field theory of a disordered t-t%26apos;-J model, we identify three aspects of the oxygen dopants related to inhomogeneity: (i) the superexchange interaction is locally enhanced in the vicinity of oxygen dopants, which enhances the local pairing gap and reduces the coherence peak; (ii) oxygen dopants donate holes into the CuO2 plane, which reduces the spinon density of states and hence the average gap at large doping; and (iii) holes are locally attracted to the vicinity of oxygen dopants, which causes an impurity bound state and further reduces the coherence peak. The interplay of these mechanisms simultaneously explains the locally enhanced pairing gap around oxygen dopants and the reduction of average gap with increasing oxygen concentration, as observed by scanning tunneling microscopy.
- 出版日期2012-3-2
