Anisotropy in the thermal hysteresis of resistivity and charge density wave nature of single crystal SrFeO3-δ: X-ray absorption and photoemission studies
Journal
Scientific Reports
Journal Volume
7
Journal Issue
1
Pages
1-11
Date Issued
2017
Author(s)
Hsieh, S. H.
Solanki, R. S.
Wang, Y. F.
Shao, Y. C.
Lee, S. H.
Yao, C. H.
Du, C. H.
Wang, H. T.
Chiou, J. W.
Chin, Y. Y.
Tsai, H. M.
Chen, J. L.
Pao, C. W.
Cheng, C. M.
Chen, W. C.
Lin, H. J.
Lee, J. F.
Pong, W. F.
Abstract
The local electronic and atomic structures of the high-quality single crystal of SrFeO3-δ (δ~0.19) were studied using temperature-dependent x-ray absorption and valence-band photoemission spectroscopy (VB-PES) to investigate the origin of anisotropic resistivity in the ab-plane and along the c-axis close to the region of thermal hysteresis (near temperature for susceptibility maximum, Tm~78 K). All experiments herein were conducted during warming and cooling processes. The Fe L 3,2-edge X-ray linear dichroism results show that during cooling from room temperature to below the transition temperature, the unoccupied Fe 3d e g states remain in persistently out-of-plane 3d 3z2-r2 orbitals. In contrast, in the warming process below the transition temperature, they change from 3d 3z2-r2 to in-plane 3d x2-y2 orbitals. The nearest-neighbor (NN) Fe-O bond lengths also exhibit anisotropic behavior in the ab-plane and along the c-axis below Tm. The anisotropic NN Fe-O bond lengths and Debye-Waller factors stabilize the in-plane Fe 3d x2-y2 and out-of-plane 3d 3z2-r2 orbitals during warming and cooling, respectively. Additionally, a VB-PES study further confirms that a relative band gap opens at low temperature in both the ab-plane and along the c-axis, providing the clear evidence of the charge-density-wave nature of SrFeO3-δ (δ~0.19) single crystal.
Publisher
Nature Publishing Group
Type
journal article