title: Quasiparticle interference of C2-symmetric surface states in a LaOFeAs parent compound.
abstract: We present scanning tunneling microscopy studies of the LaOFeAs parent compound of iron pnictide superconductors. High resolution spectroscopic imaging reveals strong standing wave patterns induced by quasiparticle interference of two-dimensional surface states. Fourier analysis shows that the distribution of scattering wave vectors exhibits pronounced twofold (C(2)) symmetry, strongly reminiscent of the nematic electronic state found in CaFe(1.94)Co(0.06)As(2). The implications of these results to the electronic structure of the pnictide parent states will be discussed.
authors.affiliation: Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Haidian, Beijing 100084, People's Republic of China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhou
authors.forename: Cun
authors.initials: C
authors.lastname: Ye
authors.forename: Peng
authors.initials: P
authors.lastname: Cai
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Wang
authors.forename: Xianhui
authors.initials: X
authors.lastname: Chen
authors.forename: Yayu
authors.initials: Y
authors.lastname: Wang