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Tebyani A, Schramm S, Hesselberth M, Boltje D, Jobst J, Tromp R, van der Molen SJ. Low energy electron microscopy at cryogenic temperatures. Ultramicroscopy 2023; 253:113815. [PMID: 37480839 DOI: 10.1016/j.ultramic.2023.113815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/16/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
We describe a cryogenic sample chamber for low energy electron microscopy (LEEM), and present first experimental results. Modifications to our IBM/SPECS aberration-corrected LEEM instrument are presented first. These include incorporation of mechanisms for cooling the sample and its surroundings, and reduction of various sources of heat load. Using both liquid nitrogen and liquid helium, we have reached sample temperatures down to about 15 K. We also present first results for low-temperature LEEM, obtained on a three-monolayer pentacene film. Specifically, we observe a reduction of the electron beam irradiation damage cross-section at 15 eV by more than a factor of five upon cooling from 300 K down to 52 K. We also observe changes in the LEEM-IV spectra of the sample upon cooling, and discuss possible causes.
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Affiliation(s)
- Arash Tebyani
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Sebastian Schramm
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Marcel Hesselberth
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Daan Boltje
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Johannes Jobst
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands
| | - Rudolf Tromp
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands; IBM T. J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, New York, New York 10598, USA
| | - Sense Jan van der Molen
- Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, P.O. Box 9504, RA Leiden NL-2300, Netherlands.
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Walker M, Scott K, Boyle TJ, Byland JK, Bötzel S, Zhao Z, Day RP, Zhdanovich S, Gorovikov S, Pedersen TM, Klavins P, Damascelli A, Eremin IM, Gozar A, Taufour V, da Silva Neto EH. Electronic stripe patterns near the fermi level of tetragonal Fe(Se,S). NPJ QUANTUM MATERIALS 2023; 8:60. [PMID: 38666239 PMCID: PMC11041788 DOI: 10.1038/s41535-023-00592-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 10/05/2023] [Indexed: 04/28/2024]
Abstract
FeSe1-xSx remains one of the most enigmatic systems of Fe-based superconductors. While much is known about the orthorhombic parent compound, FeSe, the tetragonal samples, FeSe1-xSx with x > 0.17, remain relatively unexplored. Here, we provide an in-depth investigation of the electronic states of tetragonal FeSe0.81S0.19, using scanning tunneling microscopy and spectroscopy (STM/S) measurements, supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical modeling. We analyze modulations of the local density of states (LDOS) near and away from Fe vacancy defects separately and identify quasiparticle interference (QPI) signals originating from multiple regions of the Brillouin zone, including the bands at the zone corners. We also observe that QPI signals coexist with a much stronger LDOS modulation for states near the Fermi level whose period is independent of energy. Our measurements further reveal that this strong pattern appears in the STS measurements as short range stripe patterns that are locally two-fold symmetric. Since these stripe patterns coexist with four-fold symmetric QPI around Fe-vacancies, the origin of their local two-fold symmetry must be distinct from that of nematic states in orthorhombic samples. We explore several aspects related to the stripes, such as the role of S and Fe-vacancy defects, and whether they can be explained by QPI. We consider the possibility that the observed stripe patterns may represent incipient charge order correlations, similar to those observed in the cuprates.
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Affiliation(s)
- M. Walker
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - K. Scott
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - T. J. Boyle
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - J. K. Byland
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - S. Bötzel
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
| | - Z. Zhao
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - R. P. Day
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - S. Zhdanovich
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - S. Gorovikov
- Canadian Light Source, Saskatoon, Saskatchewan Canada
| | | | - P. Klavins
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - A. Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, BC Canada
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC Canada
| | - I. M. Eremin
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
| | - A. Gozar
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
| | - V. Taufour
- Department of Physics and Astronomy, University of California, Davis, CA USA
| | - E. H. da Silva Neto
- Department of Physics and Astronomy, University of California, Davis, CA USA
- Department of Physics, Yale University, New Haven, CT USA
- Energy Sciences Institute, Yale University, West Haven, CT USA
- Department of Applied Physics, Yale University, New Haven, CT USA
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