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Jangid R, Hagström NZ, Madhavi M, Rockwell K, Shaw JM, Brock JA, Pancaldi M, De Angelis D, Capotondi F, Pedersoli E, Nembach HT, Keller MW, Bonetti S, Fullerton EE, Iacocca E, Kukreja R, Silva TJ. Extreme Domain Wall Speeds under Ultrafast Optical Excitation. PHYSICAL REVIEW LETTERS 2023; 131:256702. [PMID: 38181360 DOI: 10.1103/physrevlett.131.256702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/05/2023] [Accepted: 11/08/2023] [Indexed: 01/07/2024]
Abstract
Time-resolved ultrafast EUV magnetic scattering was used to test a recent prediction of >10 km/s domain wall speeds by optically exciting a magnetic sample with a nanoscale labyrinthine domain pattern. Ultrafast distortion of the diffraction pattern was observed at markedly different timescales compared to the magnetization quenching. The diffraction pattern distortion shows a threshold dependence with laser fluence, not seen for magnetization quenching, consistent with a picture of domain wall motion with pinning sites. Supported by simulations, we show that a speed of ≈66 km/s for highly curved domain walls can explain the experimental data. While our data agree with the prediction of extreme, nonequilibrium wall speeds locally, it differs from the details of the theory, suggesting that additional mechanisms are required to fully understand these effects.
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Affiliation(s)
- Rahul Jangid
- Department of Materials Science and Engineering, University of California Davis, Davis, California, USA
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Nanna Zhou Hagström
- Department of Materials Science and Engineering, University of California Davis, Davis, California, USA
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Meera Madhavi
- Department of Materials Science and Engineering, University of California Davis, Davis, California, USA
| | - Kyle Rockwell
- Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, Colorado Springs, Colorado, USA
| | - Justin M Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, USA
| | - Jeffrey A Brock
- Center for Memory and Recording Research, University of California San Diego, La Jolla, California, USA
| | - Matteo Pancaldi
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Dario De Angelis
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Flavio Capotondi
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Emanuele Pedersoli
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Hans T Nembach
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Associate, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Mark W Keller
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, USA
| | - Stefano Bonetti
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, 30172 Venezia, Italy
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California San Diego, La Jolla, California, USA
| | - Ezio Iacocca
- Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, Colorado Springs, Colorado, USA
| | - Roopali Kukreja
- Department of Materials Science and Engineering, University of California Davis, Davis, California, USA
| | - Thomas J Silva
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, USA
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Cao J, Ye L, He D, Zheng X, Mukamel S. Magnet-Free Time-Resolved Magnetic Circular Dichroism with Pulsed Vector Beams. J Phys Chem Lett 2022; 13:11300-11306. [PMID: 36449825 DOI: 10.1021/acs.jpclett.2c03370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Magnetic circular dichroism (MCD) is a widely used spectroscopic technique which reveals valuable information about molecular geometry and electronic structure. However, the weak signal and the necessary strong magnets impose major limitations on its application. We propose a novel protocol to overcome these limitations by using pulsed vector beams (VBs), which consist of nanosecond gigahertz pump and femtosecond UV-vis probe pulses. By virtue of the strong longitudinal electromagnetic fields, the MCD signal detected by using the pulsed VBs is greatly enhanced compared to conventional MCD performed with plane waves. Furthermore, varying the pump-probe time delay allows monitoring the ultrafast variation of molecular properties.
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Affiliation(s)
- Jiaan Cao
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Lyuzhou Ye
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Dawei He
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiao Zheng
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Shaul Mukamel
- Department of Chemistry and Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
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