Article
Physics, Applied
Vivek Unikandanunni, Rajasekhar Medapalli, Eric E. Fullerton, Karel Carva, Peter M. Oppeneer, Stefano Bonetti
Summary: In this study, ultrafast spin dynamics in an epitaxial hcp(1 1 00) cobalt thin film were investigated, revealing different demagnetization and recovery times along the easy and hard magnetic axes. The dynamics along the easy magnetization axis were found to be 33% slower, attributed to magneto-crystalline anisotropy of the electron-phonon coupling supported by ab initio calculations. This highlights the significant and previously undisclosed role of anisotropic electron-lattice coupling in ultrafast magnetism.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Wen-Tian Lu, Zhe Yuan
Summary: An ultrafast spin current induced by femtosecond laser excitation in a ferromagnetic (FM) thin film can generate transient spin accumulation in a nonmagnetic (NM) metal. The decay of spin accumulation near the FM/NM interface follows an exponential pattern and is influenced by the effective mean free path.
Article
Chemistry, Multidisciplinary
Hovan Lee, Cedric Weber, Manfred Faehnle, Mostafa Shalaby
Summary: Using a long wavelength terahertz pump-optical probe setup, the study found that complete demagnetization in magnetic systems is possible with < 6 THz pulses, accompanied by longitudinal acoustic phonons and an electronic response on the ultrafast time scale.
APPLIED SCIENCES-BASEL
(2021)
Article
Multidisciplinary Sciences
Quentin Remy, Julius Hohlfeld, Maxime Verges, Yann Le Guen, Jon Gorchon, Gregory Malinowski, Stephane Mangin, Michel Hehn
Summary: Under laser illumination, a ferromagnet can lose its magnetization through ultrafast demagnetization and phase transition. By overcoming the critical slowing down, magnetization can be reversed in a few hundreds of femtoseconds through ultrafast spin cooling and spin heating mechanisms. This has potential applications in ultrafast and energy efficient magnetic memory and storage devices.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Bingyu Ji, Zuanming Jin, Guanjie Wu, Jugeng Li, Caihua Wan, Xiufeng Han, Zongzhi Zhang, Guohong Ma, Yan Peng, Yiming Zhu
Summary: Understanding ultrafast spin dynamics is essential for future magnetic memory and storage applications. We investigated the magneto-optical response of a CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ) under short laser pulses. The results show rapid decrease of magnetization in the range of 0.33-0.37 ps, driven by electron-spin scattering and spin transport. Energy from the electron and spin reservoirs subsequently transfers to the lattice through electron-phonon and spin-phonon interactions. These findings highlight the role of the MTJ interface in spin dynamics, aiding the design and application of opto-spintronic tunnel junction stacks.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Junxiao Yu, Haijuan Zhang, Zefang Lv, Conglong Chen, Runze Li, Xiaofang Zhai, Jie Chen, Peter M. Rentzepis
Summary: This study investigates the propagation of coherent longitudinal acoustic phonons (CLAPs) in crystal materials on thin-film interfaces and heterojunctions using ultrafast optical reflectivity and ultrafast x-ray diffraction measurements. The results show that acoustic impedance matching facilitates efficient propagation of CLAPs between different thin films and substrates, while impedance mismatch partially confines CLAPs within the film.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Quentin Remy
Summary: We propose an extension to simple s-d models to simulate ultrafast magnetization dynamics and spin transport in metallic heterostructures. We introduce an alternative spin dissipation channel caused by a finite exchange splitting of the s band and identify three different mechanisms governing the dynamics of spin accumulation. Based on our theory, we explain the subpicosecond reversal of a ferromagnet in rare-earth free spin valves and support the conclusion of J. Igarashi et al. favoring magnetization reversal due to the rotation of the spin polarization of a reflected spin current.
Article
Chemistry, Multidisciplinary
Surya Narayan Panda, Sudip Majumder, Samiran Choudhury, Arpan Bhattacharya, Sumona Sinha, Anjan Barman
Summary: This study investigates the magnetization dynamics in graphene/ferromagnet hybrid heterostructures and reveals an inverse relationship between ultrafast demagnetization time and Gilbert damping parameter, induced by interfacial spin accumulation and pure spin-current transport. The findings can contribute to the understanding of magnetic damping and aid in the design of graphene-based ultrahigh-speed spintronic devices.
Article
Chemistry, Multidisciplinary
Sucheta Mondal, Yuxuan Lin, Debanjan Polley, Cong Su, Alex Zettl, Sayeef Salahuddin, Jeffrey Bokor
Summary: This paper investigates the modulation of ultrafast magnetization dynamics at graphene/ferrimagnet interfaces. The experimental results show that increasing the number of graphene layers can change the dynamical parameters, resulting in faster demagnetization time, damping, and other variations. This effect is most pronounced at the interfaces with monolayer graphene and graphite.
Article
Materials Science, Multidisciplinary
Surya Narayan Panda, Sucheta Mondal, Sudip Majumder, Anjan Barman
Summary: In this study, the effects of femtosecond laser pulses on the magnetization dynamics in Ni80Fe20 thin films were investigated using time-resolved magneto-optical Kerr effect magnetometry. The experimental results show significant changes in the magnetization dynamics, including variations in demagnetization time, remagnetization time, enhancement of the Gilbert damping parameter, and a redshift in the precessional frequency, with increasing excitation energy. It was experimentally verified that spin-flip scattering and intraband electron conductivity contribute to the ultrafast demagnetization and damping processes.
Article
Chemistry, Physical
Xianshao Zou, Robert Bericat Vadell, Bin Cai, Xinjian Geng, Ananta Dey, Yawen Liu, Axel Gudmundsson, Jie Meng, Jacinto Sa
Summary: Optical upconversion via a multiphoton absorption process converts low-energy photons to shorter wavelengths. A solid-state thin film for infrared-to-visible upconversion composed of plasmonic/TiO2 interfaces is reported in this study. When excited at & lambda; = 800 nm, three photons are absorbed, leading to the excitation of TiO2 trap states into an emissive state in the visible domain. The plasmonic nanoparticle enhances the light absorption capabilities of the semiconductor, increasing emission efficiency by 20 times.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Physics, Multidisciplinary
Shujuan Yan, Qingyun Xu, Xinyu Hao, Ying Guo, Jing Guo
Summary: By numerically solving time-dependent Schrodinger equations, the generation process of electron currents, ultrafast magnetic fields and photoelectron momentum distributions (PMD) in the interaction between circularly polarized laser pulses and a Ne dimer during charge migration (CM) process is investigated. Two cases are considered by adjusting the laser wavelength: (i) coherent resonance excitation (lambda = 76 nm) and (ii) direct ionization (lambda = 38 nm). The results demonstrate that the current and magnetic field generated under resonance excitation are stronger than under direct ionization due to the quantum interference between the initial and excited states. Additionally, periodic oscillating currents are observed for the Ne dimer under different ionization conditions. These findings lay a foundation for the study of ultrafast magnetism in complex molecular systems.
CHINESE PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
G. Stegmann, W. Toews, G. M. Pastor
Summary: This study presents an electronic theory of laser-induced ultrafast magnetization dynamics in transition-metal alloys. A many-body model Hamiltonian is used to incorporate electronic hopping, local Coulomb interaction, and spin-orbit coupling (SOC). Time propagations are performed on a tetrahedral cluster to obtain the time dependencies of local spin moments, orbital occupations, and single-particle energies for homogeneous systems and binary alloys. The effects of laser absorption inhomogeneities and SOC strengths on spin-density transfers between alloy components are investigated. A local perspective on optically induced spin transfer is proposed, involving dominantly local optical excitation followed by hopping-driven spin-density transfers among different alloy components. The role of electron delocalization and electronic hopping in spin-density redistribution and demagnetization of alloy components is demonstrated.
Article
Physics, Applied
Xiaowen Chen, Roman Adam, Fangzhou Wang, Yawen Song, Lining Pan, Chengkun Song, Sarah Heidtfeld, Christian Greb, Qiuyue Li, Jing Yu, Jing Zhang, Yuanzhi Cui, Shandong Li, Jie Xu, Mirko Cinchetti, Claus M. Schneider, Derang Cao
Summary: We investigated the effect of thickness gradient on magnetization dynamics in a ferromagnetic Ni80Fe20 film. The observed magnetization reorientation and stripe domain formation led to faster demagnetization and magnetization recovery in the thicker part of the film. Both experiments and micromagnetic simulations supported the role of magnetic anisotropy introduced by stripe domain formation in the decrease of relaxation time. Our findings highlight the significance of micromagnetic structure in the magnetization dynamics of ferromagnetic films after optically triggered demagnetization.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
M. J. G. Peeters, Y. M. van Ballegooie, B. Koopmans
Summary: This study experimentally resolves the dynamics of the switching process in Co/Gd and investigates the influence of applied magnetic fields on the process. The research finds that after a switch within several picoseconds, the magnetization switches back at a time scale of hundreds of picoseconds. This backswitch shows a strong dependence on the magnetic field strength, even at subtesla fields.
Editorial Material
Physics, Condensed Matter
Andrea Eschenlohr, Uwe Bovensiepen
JOURNAL OF PHYSICS-CONDENSED MATTER
(2018)
Article
Physics, Multidisciplinary
M. Ligges, I. Avigo, D. Golez, H. U. R. Strand, Y. Beyazit, K. Hanff, F. Diekmann, L. Stojchevska, M. Kallane, P. Zhou, K. Rossnagel, M. Eckstein, P. Werner, U. Bovensiepen
PHYSICAL REVIEW LETTERS
(2018)
Article
Multidisciplinary Sciences
Tatiana Konstantinova, Jonathan D. Rameau, Alexander H. Reid, Omadillo Abdurazakov, Lijun Wu, Renkai Li, Xiaozhe Shen, Genda Gu, Yuan Huang, Laurenz Rettig, Isabella Avigo, Manuel Ligges, James K. Freericks, Alexander F. Kemper, Hermann A. Duerr, Uwe Bovensiepen, Peter D. Johnson, Xijie Wang, Yimei Zhu
Article
Chemistry, Multidisciplinary
Isabella Avigo, Ping Zhou, Matthias Kallaene, Kai Rossnagel, Uwe Bovensiepen, Manuel Ligges
APPLIED SCIENCES-BASEL
(2019)
Correction
Physics, Multidisciplinary
M. Ligges, I. Avigo, D. Golez, H. U. R. Strand, Y. Beyazit, K. Hanff, F. Diekmann, L. Stojchevska, M. Kallane, P. Zhou, K. Rossnagel, M. Eckstein, P. Werner, U. Bovensiepen
PHYSICAL REVIEW LETTERS
(2019)
Article
Chemistry, Physical
V Tinnemann, C. Streubuehr, B. Hafke, A. Kalus, A. Hanisch-Blicharski, M. Ligges, P. Zhou, D. von der Linde, U. Bovensiepen, M. Horn-von Hoegen
STRUCTURAL DYNAMICS-US
(2019)
Article
Chemistry, Physical
V. Tinnemann, C. Streubuehr, B. Hafke, T. Witte, A. Kalus, A. Hanisch-Blicharski, M. Ligges, P. Zhou, D. von der Linde, U. Bovensiepen, M. Horn-von Hoegen
STRUCTURAL DYNAMICS-US
(2019)
Article
Chemistry, Physical
Cord Bertram, Philipp Auburger, Michel Bockstedte, Julia Staebler, Uwe Bovensiepen, Karina Morgenstern
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2020)
Article
Physics, Multidisciplinary
Y. Beyazit, J. Beckord, P. Zhou, J. P. Meyburg, F. Kuehne, D. Diesing, M. Ligges, U. Bovensiepen
PHYSICAL REVIEW LETTERS
(2020)
Article
Chemistry, Physical
C. Bertram, D. P. Miller, Chr Schunke, I Kemeny, M. W. Kimura, U. Bovensiepen, E. Zurek, K. Morgenstern
Summary: The study reports the self-assembly of chlorobenzene molecules on the Cu(111) surface into nanosized clusters and investigates the role of halogen bonds and weak hydrogen bonds in nanocluster formation. Through experiments and calculations, specific binding motifs within the clusters that lead to their formation and stability are identified.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Physics, Multidisciplinary
J. Thomas, C. Bertram, J. Daru, J. Patwari, I Langguth, P. Zhou, D. Marx, K. Morgenstern, U. Bovensiepen
Summary: The study reveals the intricate impact of Xe on Cs+/Cu(111), with Xe showing both attractive and repulsive effects depending on the charge of the respective counterparticle. The attraction between Cs+ and Xe counterbalances the Coulomb repulsion between Cs+ ions on Cu(111), while the Cs 6s electron is repelled from Cu(111) due to xenon's electron density.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
N. Rothenbach, M. E. Gruner, K. Ollefs, C. Schmitz-Antoniak, S. Salamon, P. Zhou, R. Li, M. Mo, S. Park, X. Shen, S. Weathersby, J. Yang, X. J. Wang, O. Sipr, H. Ebert, K. Sokolowski-Tinten, R. Pentcheva, U. Bovensiepen, A. Eschenlohr, H. Wende
Summary: In this study, time-dependent and constituent-specific spectral changes in soft X-ray absorption spectroscopy (XAS) of an [Fe/MgO](8) metal/insulator heterostructure after laser excitation were analyzed at the O K-edge with picosecond time resolution. It was found that the oxygen absorption edge of the insulator showed a uniform intensity decrease of the fine structure at elevated phononic temperatures. The sensitivity of transient near-edge XAS to phonons was demonstrated by combining XAS with ultrafast electron diffraction measurements and ab initio calculations.
Article
Physics, Multidisciplinary
I Avigo, F. Queisser, P. Zhou, M. Ligges, K. Rossnagel, R. Schuetzhold, U. Bovensiepen
PHYSICAL REVIEW RESEARCH
(2020)
Article
Optics
Andre Seyen, Roland Kohn, Uwe Bovensiepen, Dietrich von der Linde, Alexander Tarasevitch
Article
Materials Science, Multidisciplinary
S. Freutel, J. D. Rameau, L. Rettig, I Avigo, M. Ligges, Y. Yoshida, H. Eisaki, J. Schneeloch, R. D. Zhong, Z. J. Xu, G. D. Gu, U. Bovensiepen, P. D. Johnson