Polarized X-ray absorption spectroscopic study on mercuric bromide intercalated Bi₂Sr₂CaCu₂O_ysingle crystal

Polarized X-ray absorption spectroscopic experiments have been carried out for the mercuric bromide intercalated Bi₂Sr₂CaCu₂O_ysingle crystal, in order to understand the variation of anisotropic resistivities upon HgBr₂intercalation as well as to probe the electronic structure of HgBr₂intercalate. The Br K- and Bi Lin-edge spectra indicate a significant electron transfer from bismuth to bromine, implying an overlap between Bi 6s and Br 4p orbitals. From the Hg L_III- and Br K-edge data, it is also found that HgBr₂intercalation gives rise to an electron localization in the (Hg-Br) bond, which leads to poor electronic conduction along the intercalant layer. In this context, the semiconducting out-of-plane resistivity of HgBr₂intercalate can be explained by the poor conductivity of the intercalated HgBr₂layer, even though the orbital overlap between Bi and Br facilitates the electron conduction between host and guest along the c-axis.