Transition from tunneling regime to local point contact realized on Ba0.6K0.4Fe2As2 surface*

Project supported by the National Natural Science Foundation of China (Grant Nos. 11574372 and 11322432) and the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences (Grant No. XDB07020300).

Hou Xingyuan1, 2, Jie Yunyin1, 2, Gong Jing1, 2, Shen Bing2, Zi Hai2, Li Chunhong2, Ren Cong2, Shan Lei1, 2, 3, †
       

(color online) (a) A topographic image of an in situ-cleaved surface of Ba Fe As . (b) A DOS map, measured on the same field of view as Fig. 1(a) at zero sample bias. (c) Enlarged view of the lower impurity in Fig. 1(b). (d) and (e) Tunneling spectra measured along the lateral and vertical trajectories in Fig. 1(c), respectively. (f) Spatial dependence of zero-bias conductance along the two trajectories. The solid line is a fit to Gauss function with characteristic width of nm. (g) Three typical spectra taken at the specific positions labeled in Fig. 1(c). All the data presented here were taken at sample bias mV and setting current pA with temperature T = 3 K.