Ultrafast Modulation of the Chemical Potential in BaFe 2 As 2 by Coherent Phonons

作者：Lexian Yang, G. Rohde, Timm Rohwer, A. Stange, K. Hanff, Christian Sohrt, Laurenz Rettig, R. Cortés, F. Chen, D. L. Feng, Thomas Wolf, Bhaskar Kamble, Ilya Eremin, Tenio Popmintchev, Margaret M. Murnane, Henry C. Kapteyn, L. Kipp, J. Fink, Michael Bauer, U. Bovensiepen, Kai Roßnagel · 发表于：Physical Review Letters · 年份：2014 · DOI：10.1103/physrevlett.112.207001 · 被引用次数：69 · 研究领域：Iron-based superconductors research、Intellectual Capital and Performance Analysis

Time- and angle-resolved extreme ultraviolet photoemission spectroscopy is used to study the electronic structure dynamics in ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$ around the high-symmetry points $\mathrm{\ensuremath{\Gamma}}$ and $M$. A global oscillation of the Fermi level at the frequency of the ${A}_{1g}(\mathrm{As})$ phonon mode is observed. It is argued that this behavior reflects a modulation of the effective chemical potential in the photoexcited surface region that arises from the high sensitivity of the band structure near the Fermi level to the ${A}_{1g}(\mathrm{As})$ phonon mode combined with a low electron diffusivity perpendicular to the layers. The results establish a novel way to tune the electronic properties of iron pnictides: coherent control of the effective chemical potential. The results further suggest that the equilibration time for the effective chemical potential needs to be considered in the ultrafast electronic structure dynamics of materials with weak interlayer coupling.