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Chen HY, Versteeg RB, Mankowsky R, Puppin M, Leroy L, Sander M, Deng Y, Oggenfuss RA, Zamofing T, Böhler P, Pradervand C, Mozzanica A, Vetter S, Smolentsev G, Kerkhoff L, Lemke HT, Chergui M, Mancini GF. A setup for hard x-ray time-resolved resonant inelastic x-ray scattering at SwissFEL. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:024308. [PMID: 38586277 PMCID: PMC10998714 DOI: 10.1063/4.0000236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/04/2024] [Indexed: 04/09/2024]
Abstract
We present a new setup for resonant inelastic hard x-ray scattering at the Bernina beamline of SwissFEL with energy, momentum, and temporal resolution. The compact R = 0.5 m Johann-type spectrometer can be equipped with up to three crystal analyzers and allows efficient collection of RIXS spectra. Optical pumping for time-resolved studies can be realized with a broad span of optical wavelengths. We demonstrate the performance of the setup at an overall ∼180 meV resolution in a study of ground-state and photoexcited (at 400 nm) honeycomb 5d iridate α-Li2IrO3. Steady-state RIXS spectra at the iridium L3-edge (11.214 keV) have been collected and are in very good agreement with data collected at synchrotrons. The time-resolved RIXS transients exhibit changes in the energy loss region <2 eV, whose features mostly result from the hopping nature of 5d electrons in the honeycomb lattice. These changes are ascribed to modulations of the Ir-to-Ir inter-site transition scattering efficiency, which we associate to a transient screening of the on-site Coulomb interaction.
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Affiliation(s)
- Hui-Yuan Chen
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Rolf B. Versteeg
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Roman Mankowsky
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Michele Puppin
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | | | - Mathias Sander
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Yunpei Deng
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | | | - Thierry Zamofing
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Pirmin Böhler
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Claude Pradervand
- Photon Science Division, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Aldo Mozzanica
- Photon Science Division, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Seraphin Vetter
- Photon Science Division, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Grigory Smolentsev
- Energy and Environment Research Division, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Linda Kerkhoff
- Sect. Crystallography, Institute of Geology and Mineralogy, University of Cologne, 50674 Köln, Germany
| | - Henrik T. Lemke
- SwissFEL, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Majed Chergui
- Authors to whom correspondence should be addressed: and
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Shen K, Sun K, Gelin MF, Zhao Y. Finite-Temperature Hole-Magnon Dynamics in an Antiferromagnet. J Phys Chem Lett 2024; 15:447-453. [PMID: 38189682 DOI: 10.1021/acs.jpclett.3c03298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Employing the numerically accurate multiple Davydov Ansatz in combination with the thermo-field dynamics approach, we delve into the interplay of the finite-temperature dynamics of holes and magnons in an antiferromagnet, which allows for scrutinizing previous predictions from the self-consistent Born approximation while offering, for the first time, accurate finite-temperature computation of detailed magnon dynamics as a response and a facilitator to the hole motion. The study also uncovers a pronounced temperature dependence of the magnon and hole populations, pointing to the feasibility of potential thermal manipulation and control of hole dynamics. Our methodology can be applied not only to the calculation of steady-state angular-resolved photoemission spectra but also to the simulation of femtosecond terahertz pump-probe and other nonlinear signals for the characterization of antiferromagnetic materials.
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Affiliation(s)
- Kaijun Shen
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Kewei Sun
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Maxim F Gelin
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Yang Zhao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
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Dodge JS, Lopez L, Sahota DG. Optical Saturation Produces Spurious Evidence for Photoinduced Superconductivity in K_{3}C_{60}. PHYSICAL REVIEW LETTERS 2023; 130:146002. [PMID: 37084450 DOI: 10.1103/physrevlett.130.146002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/09/2022] [Accepted: 02/10/2023] [Indexed: 05/03/2023]
Abstract
We discuss a systematic error in time-resolved optical conductivity measurements that becomes important at high pump intensities. We show that common optical nonlinearities can distort the photoconductivity depth profile, and by extension distort the photoconductivity spectrum. We show evidence that this distortion is present in existing measurements on K_{3}C_{60}, and describe how it may create the appearance of photoinduced superconductivity where none exists. Similar errors may emerge in other pump-probe spectroscopy measurements, and we discuss how to correct for them.
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Affiliation(s)
- J Steven Dodge
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Leya Lopez
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Derek G Sahota
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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Enhanced Ultrafast Broadband Reverse Saturable Absorption in Twistacenes with Enlarged π-Conjugated Central Bridge. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27249059. [PMID: 36558191 PMCID: PMC9782705 DOI: 10.3390/molecules27249059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/13/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
Optical nonlinearities of two all-carbon twistacenes, DPyA and DPyN, with the different π-conjugated central bridges were investigated. The nonlinear absorption properties of these compounds were measured using the femtosecond Z-scan with wavelengths between 650 and 900 nm. It has been found that the nonlinear absorption originated from two-photon absorption (TPA) and TPA-induced excited state absorption (ESA), wherein DPyA demonstrates higher performance than DPyN. The TPA cross section of DPyA (4300 GM) is nearly 4.3 times larger than that of DPyN at 650 nm. Moreover, the different central structures modulate the intensity of ESA at 532 nm, and DPyA exhibits an excellent ESA at 532 nm with multi-pulse excitation. Meanwhile, the result of data fitting and quantum chemistry calculation shows that the enhancement of nonlinear absorption in DPyA is due to the extended π- conjugated bridge and improved delocalization of π-electrons. These all-carbon twistacenes could yield potential applications in optical power limiting (OPL) technology.
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