We use scanning tunnelling microscopy and spectroscopy to explore the electronic structure of Fe1.07Te which is the parent compound of the iron-chalcogenide superconductors. A unidirectional electronic structure with a period of a0 (where a0 is the lattice constant) along the a-axis is observed. The unidirectional pattern is visible within an energy range from approximately -200 to +130 meV. Since the direction of the unidirectional electronic structure coincides with those of the underlying antiferromagnetic and the predicted orbital orders, it is presumable that the observed unidirectional structure is closely tied to these orders and is peculiar to the parent state in iron-based superconductors.
@article{arxiv.1105.4754,
title = {Unidirectional Electronic Structure in the Parent State of Iron-Chalcogenide Superconductor Fe$_{1+\delta}$Te},
author = {Tadashi Machida and Kazuho Kogure and Takuya Kato and Hiroshi Nakamura and Hiroyuki Takeya and Takashi Mochiku and Shuuichi Ooi and Yoshikazu Mizuguchi and Yoshihiko Takano and Kazuto Hirata and Hideaki Sakata},
journal= {arXiv preprint arXiv:1105.4754},
year = {2013}
}