Orbital selective dynamics in Fe-pnictides triggered by polarized pump pulse excitations
- 1 October 2021
- journal article
- research article
- Published by IOP Publishing in Europhysics Letters
- Vol. 136 (1), 17002
- https://doi.org/10.1209/0295-5075/ac2dc0
Abstract
Quantum materials display exotic behaviours related to the interplay between temperature-driven phase transitions. Here, we study the electron dynamics in one such material, CaFe$_2$As$_2$, a parent Fe-based superconductor, employing time and angle-resolved photoemission spectroscopy. CaFe$_2$As$_2$ exhibits concomitant transition to spin density wave state and tetragonal to orthorhombic structure below 170 K. The Fermi surface of this material consists of three hole pockets ($\alpha$, $\beta$ and $\gamma$) around $\Gamma$-point and two electron pockets around $X$-point. The hole pockets have $d_{xy}$, $d_{yz}$ and $d_{zx}$ orbital symmetries. The $\beta$ band constituted by $d_{xz}$/$d_{yz}$ orbitals exhibit a gap across the magnetic phase transition. We discover that polarized pump pulses can induce excitations of electrons of a selected symmetry. More specifically, while $s$-polarized light (polarization vector perpendicular to the $xz$-plane) excites electrons corresponding to all the three hole bands, $p$-polarized light excites electrons essentially from ($\alpha$,$\beta$) bands which are responsible for magnetic order. Interestingly, within the magnetically ordered phase, the excitation due to the $p$-polarized pump pulses occur at a time scale of 50 fs, which is significantly faster than the excitation induced by $s$-polarized light ($\sim$ 200 fs). These results suggest that the relaxation of different ordered phases occurs at different time scales and this method can be used to achieve selective excitations to disentangle complexity in the study of quantum materials.
Keywords
Funding Information
- Department of Atomic Energy, Government of India
- European Unions Horizon 2020 (654360 NFFA-Europe)
This publication has 31 references indexed in Scilit:
- Pressure-decoupled magnetic and structural transitions of the parent compound of iron-based 122 superconductors BaFe 2 As 2Proceedings of the National Academy of Sciences of the United States of America, 2013
- Electronic structure of EuFe2As2Journal of Physics: Condensed Matter, 2013
- Magnetism and its microscopic origin in iron-based high-temperature superconductorsNature Physics, 2012
- Observation of a coherent optical phonon in the iron pnictide superconductor ( and 0.08)Physical Review B, 2009
- Measurement of Anomalous Phonon Dispersion ofSingle Crystals Using Inelastic Neutron ScatteringPhysical Review Letters, 2009
- Anisotropic magnetic and superconducting properties ofsingle crystalsPhysical Review B, 2009
- Transient Electronic Structure and Melting of a Charge Density Wave in TbTe 3Science, 2008
- Lattice and magnetic instabilities in: A single-crystal neutron diffraction studyPhysical Review B, 2008
- Iron-Based Layered Superconductor La[O1-xFx]FeAs (x = 0.05−0.12) with Tc = 26 KJournal of the American Chemical Society, 2008
- Iron-Based Layered Superconductor: LaOFePJournal of the American Chemical Society, 2006