摘要
We performed a combined angle-resolved photoemission spectroscopy and scanning tunneling microscopy study of the electronic structure of electron-doped Ca_(0.83)La_(0.17)Fe_(2)As_(2).A surface reconstruction associated with the dimerization of As atoms is observed directly in the real space,as well as the consequent band folding in the momentum space.Besides this band folding effect,the Fermi surface topology of this material is similar to that reported previously for BaFe_(1.85)Co_(0.15)As_(2),with Γ-centered hole pockets quasi-nested to M-centered electron pockets by the antiferromagnetic wave vector.Although no superconducting gap is observed by ARPES possibly due to low superconducting volume fraction,a gap-like density of states depression of 7.7±2.9 meV is determined by scanning tunneling microscopy.
基金
Supported by Chinese Academy of Sciences(2010Y1JB6)
the National Basic Research Program of China(2010CB923000 and 2011CBA001000)
the National Natural Science Foundation of China(11004232 and 11050110422)
the Sino-Swiss Science and Technology Cooperation(No IZLCZ2138954)
The work in Houston is supported in part by US Air Force Office of Scientific Research under Contract No FA9550-09-1-0656
Department of Energy Subcontract No 4000086706 through ORNL,AFRL Subcontract No R15901(CONTACT)through Rice University,the T.L.L.Temple Foundation and the John J.and Rebecca Moores Endowment,and the State of Texas through TCSUH.
