Observation of the bands with $d_{xy}$ orbital character near the Fermi level in NdFeAs${}_{1-x}$P${}_x$O${}_{0.9}$F${}_{0.1}$ using angle-resolved photoemission spectroscopy

Abstract

We studied the band structure of NdFeAs${}_{1-x}$P${}_x$O${}_{0.9}$F${}_{0.1}$ ($x$ = 0, 0.2, 0.4 and 0.6) using angle-resolved photoemission spectroscopy (ARPES) measurements. Two of the hole bands, ${\alpha }_1$ $(d_{xz})$ and ${\alpha }_3$ $(d_{z^2})$, were observed at the Brillouin zone center in the $P$-polarized light configuration, while the other two hole bands, ${\alpha }_2$ $(d_{yz})$ and $\gamma$ $(d_{xy})$, were observed in the $S$-polarized alternative. The observed $\gamma$ band shifts downwards as $x$ increases, which is consistent with the theoretical prediction for the change in bond angle of As/P-Fe-As/P. Furthermore, a small amount of the $d_{xy}$ orbital component was observed at the same binding energy as that of the top of the ${\alpha }_1$ band, thus indicating the band reconstruction of the originally degenerate ${\alpha }_1$ and ${\alpha }_2$ $(d_{xz}/d_{yz})$ bands by the unoccupied $d_{xy}$ band. The change in the energy level of the ${\alpha }_1$ band top with $d_{xy}$ orbital character is accompanied by a $T_c$ upturn at $0.2<x<0.4$. The $T_c$ continues to increase as the ${\alpha }_1$ band shifts downward, crossing the Fermi level. The incipient band with the $d_{xy}$ orbital character on its top could be an important ingredient for high $T_c$ 1111-type iron-based superconductors.

10 pages, 7 figures, Accepted for publication in Phys. Rev. B

References in corpus (15)

• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• The electronic phase diagram of the LaO1-xFxFeAs superconductor
• Crystallographic Phase Transition and High-Tc Superconductivity in LaFeAsO:F
• Bandwidth and Fermi surface of Iron-Oxypnictides: covalency and sensitivity to structural changes
• Observation of strong electron pairing on bands without Fermi surfaces in LiFe1-xCoxAs
• Superconductivity and its mechanism in an ab initio model for electron-doped LaFeAsO
• Surface and bulk electronic structures of LaOFeAs studied by angle resolved photoemission spectroscopy
• Maximizing Fermi surface multiplicity optimizes superconductivity in iron pnictides
• Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor
• Detailed band structure of twinned and detwinned BaFe${}_2$As${}_2$ studied with angle-resolved photoemission spectroscopy
• Superconductivity at 52 K in hydrogen-substituted LaFeAsO1-xHx under high pressure
• Evolution of the Phase Diagram of LaFeP${}_{1-x}$As${}_x$O${}_{1-y}$F${}_y$ ($y$ = 0 -- 0.1)
• Origin of the non-monotonic variance of Tc in the 1111 iron based superconductors with isovalent doping
• Three superconducting phases with different categories of pairing in hole- and electron-doped LaFeAs${}_{1-x}$P${}_x$O
• Importance of dxy orbital and electron correlation in iron-based superconductors revealed by phase diagram for 1111-system