Speaker
Tetsuya Hajiri
(Nagoya University)
Description
Tetsuya Hajiri ^A, B^
Takahiro Ito ^A,C^
Ryosuke Niwa ^A^
Satoshi Hirate ^A^
Masaharu Matsunami ^B,D^
Byeong Hun Min ^E^,
Yong Seung Kwon ^E^
Shin-ichi Kimura ^B,D^
^A^ Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
^B^ UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
^C^ Nagoya University Synchrotron Radiation Research Center, Nagoya University, Nagoya, 464-8603, Japan
^D^ School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
^E^ Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea
LiFeAs is an intriguing iron-based superconductor because it exhibits superconductivity (TC = 18 K) without any structural phase and SDW/AFM transitions [1]. In pristine LiFeAs, we have demonstrated that the electronic structure can be fundamentally explained by LDA band structure [2]. In this system, both of the excess and deficiency of Li-ions (Li1+xFeAs) from the stoichiometry suppresses the superconductivity [3] and enlarges spin fluctuation [4]. Up to date, the reason of the suppression of the superconductivity has not been clarified yet. To elucidate the effect of the Li excess or deficiency, we investigated the electronic structure of non-superconducting Li1+xFeAs by a polarization-dependent three-dimensional angle-resolved photoemission spectroscopy (3D-ARPES). As a result, we observed the difference in the low-energy electronic structure between pristine LiFeAs and Li1+xFeAs. We also found two kink structures in the band dispersions near the center of the Brillouin zone; one is located at about 20 meV, which originates from phonons, and the other at about 100 meV, which cannot be explained by the phonon origin. The higher-energy kink is considered to originate from magnetic excitations.
[1] X. C. Wang et al., Solid State Commun. 148, 538-540 (2008).
[2] T. Hajiri et al., to be published in Phys. Rev. B.
[3] M. Wang et al., Phys. Rev. B 83, 220515(R) (2011).
[4] L. Ma et al., Phys. Rev. B 82, 180501(R) (2010).
Primary author
Tetsuya Hajiri
(Nagoya University)
