Article
Physics, Multidisciplinary
Andrea Cavagna, Luca Di Carlo, Irene Giardina, Tomas S. Grigera, Stefania Melillo, Leonardo Parisi, Giulia Pisegna, Mattia Scandolo
Summary: By using the renormalization group, the dynamical critical exponent of natural swarms of insects is calculated, and a new fixed point is discovered. The critical exponent at the new fixed point is consistent with both experiments and numerical simulations, indicating the power of the renormalization group in describing collective behavior.
Article
Multidisciplinary Sciences
Waldemar Toews, Gunnar Stegmann, G. M. Pastor
Summary: The study investigates the influence of spin and orbital rotational symmetry on the laser-induced magnetization dynamics of itinerant-electron ferromagnets. The ultrafast demagnetization of transition metals is shown to be a direct consequence of the breaking of these conservation laws in the electronic system, which is inherent to the nature of spin-orbit and electron-lattice interactions. Through exact numerical calculations, a comprehensive symmetry analysis is conducted on the time evolution of optically excited ferromagnetic ground states within the framework of a many-body electronic Hamiltonian. Quantitative relations are established between the strength of interactions that break rotational symmetries and the relevant time scales for magnetization dynamics.
Article
Materials Science, Multidisciplinary
Guido Giachetti, Andrea Trombettoni, Stefano Ruffo, Nicolo Defenu
Summary: In this paper, a field-theoretical treatment of the 2D XY model with long-range couplings is discussed, and it is compared with results from the self-consistent harmonic approximation. The results show that both power law BKT scaling and spontaneous symmetry breaking occur for the same decay rates of long-range interactions. Meanwhile, the Villain approximation fails to reproduce the correct critical behavior in the long-range regime.
Article
Multidisciplinary Sciences
Gyuyoung Park, Jaehak Yang, Sang-Koog Kim
Summary: We explored spin-wave multiplets excited in a different type of magnonic crystal composed of ferromagnetic antidot-lattice fractals, and found that a recursive development of geometrical fractals gives rise to the same recursive evolution of spin-wave multiplets.
SCIENTIFIC REPORTS
(2021)
Article
Materials Science, Multidisciplinary
Shuang Li, Jing Xia, Laichuan Shen, Xichao Zhang, Motohiko Ezawa, Yan Zhou
Summary: The mutual conversion between a Neel-type hopfion and a Neel-type toron under an external magnetic field is numerically studied. It is found that the Neel-type hopfion could be a stable state and transforms into a Neel-type toron at a certain magnetic field. Moreover, the hopfion and toron exhibit different excitation modes under different magnetic and microwave fields.
Article
Physics, Multidisciplinary
Kumar Neeraj, Nilesh Awari, Sergey Kovalev, Debanjan Polley, Nanna Zhou Hagstrom, Sri Sai Phani Kanth Arekapudi, Anna Semisalova, Kilian Lenz, Bertram Green, Jan-Christoph Deinert, Igor Ilyakov, Min Chen, Mohammed Bawatna, Valentino Scalera, Massimiliano D'Aquino, Claudio Serpico, Olav Hellwig, Jean-Eric Wegrowe, Michael Gensch, Stefano Bonetti
Summary: The study reveals the intrinsic inertial spin dynamics in ferromagnetic thin films, with the magnetization nutating at a frequency of -0.5 THz. This indicates that the angular momentum relaxation time in ferromagnets is on the order of 10 ps.
Article
Materials Science, Multidisciplinary
Mathias Bersweiler, Evelyn Pratami Sinaga, Inma Peral, Nozomu Adachi, Philipp Bender, Nina-Juliane Steinke, Elliot Paul Gilbert, Yoshikazu Todaka, Andreas Michels, Yojiro Oba
Summary: The combination of magnetometry and magnetic small-angle neutron scattering was used to study the effect of microstructure on the macroscopic magnetic properties of a nanocrystalline Ni bulk sample. Mechanical deformation increased coercivity significantly and caused spin-misalignment scattering due to crystal defects. The magnetic correlation length indicated an average defect size of 11 nm, smaller than the average crystallite size of 60 nm, and the strain fields around defects in the remanent state led to spin disorder in the surrounding ferromagnetic bulk.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Multidisciplinary
Guido Giachetti, Nicolo Defenu, Stefano Ruffo, Andrea Trombettoni
Summary: The article discusses the effect of long-range decaying couplings on the BKT transition, revealing a phase diagram far richer than the short-range scenario, with a quasiordered phase existing between a symmetry broken phase and a disordered phase.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Yuelei Zhao, Sheng Yang, Kai Wu, Xiaoguang Li, Xichao Zhang, Li Li, Zhiqin Chu, Chong Bi, Yan Zhou
Summary: Deterministic switching in synthetic antiferromagnets can be achieved through flexible domain control in the absence of external magnetic fields, addressing the technical challenge of requiring an in-plane magnetic field.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
D. C. Mahendra, Ding-Fu Shao, Vincent D. -H. Hou, Arturas Vailionis, P. Quarterman, Ali Habiboglu, M. B. Venuti, Fen Xue, Yen-Lin Huang, Chien-Min Lee, Masashi Miura, Brian Kirby, Chong Bi, Xiang Li, Yong Deng, Shy-Jay Lin, Wilman Tsai, Serena Eley, Wei-Gang Wang, Julie A. Borchers, Evgeny Y. Tsymbal, Shan X. Wang
Summary: By utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate, the authors observed both conventional spin-orbit torques and unconventional out-of-plane and in-plane anti-damping-like torques in MnPd3/CoFeB heterostructures, enabling complete field-free switching of perpendicular cobalt. These unconventional torques are attributed to the low symmetry of the (114)-oriented MnPd3 films. The results provide a path towards practical spin channels in ultrafast magnetic memory and logic devices.
Article
Materials Science, Multidisciplinary
Y. Oba, M. Bersweiler, I Titov, N. Adachi, Y. Todaka, E. P. Gilbert, N-J Steinke, K. L. Metlov, A. Michels
Summary: High-pressure torsion straining induces spin misalignments in pure Ni, resulting in unusual angular anisotropy scattering patterns in magnetic fields. These patterns cannot be explained by conventional micromagnetic theory, suggesting that the high density of crystal defects induced by HPT makes higher-order effects observable in micromagnetic SANS cross sections.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Multidisciplinary
Tomoki Hirosawa, Jelena Klinovaja, Daniel Loss, Sebastian A. Diaz
Summary: This study demonstrates the potential of laser fields in controlling the topological magnetic structures and excitations in multiferroic insulators. The velocity and propagation direction of skyrmions, as well as the ultrafast Floquet magnonic topological phase transition, can be tuned by the amplitude and polarization of the laser field. The magnonic thermal Hall conductivity is proposed as a new diagnostic tool for the analysis of these phenomena.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Stephen Londo, Somnath Biswas, Igor Pinchuk, Alexandra Boyadzhiev, Roland K. Kawakami, L. Robert Baker
Summary: This study reveals the mechanism of ultrafast optical spin switching in nickel ferrite and highlights the unprecedented temporal and site-specific resolution capability of extreme ultraviolet spectroscopy in elucidating these dynamics.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
David Moenkebuescher, Paul Rosenberger, Fabian Mertens, Roman Adam, Claus M. M. Schneider, Umut Parlak, Martina Mueller, Mirko Cinchetti
Summary: The magnetic proximity effect is studied in EuO/Co bilayers using magneto-optical Kerr effect measurements. Excitation above EuO bandgap results in ultrafast enhancement of EuO magnetization followed by demagnetization. The superdiffusive spin current from Co into EuO is observed as well. The bilayers provide a tunable system where the magneto-optical signal can be adjusted by external parameters, and experimental evidence for the presence of a tuneable magnetic proximity coupling between Co and EuO is given by measuring the magnetic hysteresis of EuO up to room temperature.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Physics, Applied
Julius de Rojas, Del Atkinson, Adekunle O. Adeyeye
Summary: We have investigated the static and dynamic behavior of pseudo-3D trilayer square artificial spin ice structures. By varying the thickness of the nonmagnetic copper layer, interlayer coupling between layers can be finely controlled, leading to bespoke magnetization states and resonance spectra tuning. This study provides a programmable degree of freedom for magnetization dynamics in magnonic and microwave devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
N. Meyer, K. Geishendorf, J. Walowski, A. Thomas, M. Muenzenberg
APPLIED PHYSICS LETTERS
(2020)
Review
Physics, Condensed Matter
Anjan Barman, Gianluca Gubbiotti, S. Ladak, A. O. Adeyeye, M. Krawczyk, J. Grafe, C. Adelmann, S. Cotofana, A. Naeemi, V. Vasyuchka, B. Hillebrands, S. A. Nikitov, H. Yu, D. Grundler, A. Sadovnikov, A. A. Grachev, S. E. Sheshukova, J-Y Duquesne, M. Marangolo, G. Csaba, W. Porod, V. E. Demidov, S. Urazhdin, S. O. Demokritov, E. Albisetti, D. Petti, R. Bertacco, H. Schultheiss, V. V. Kruglyak, V. D. Poimanov, S. Sahoo, J. Sinha, H. Yang, M. Munzenburg, T. Moriyama, S. Mizukami, P. Landeros, R. A. Gallardo, G. Carlotti, J- Kim, R. L. Stamps, R. E. Camley, B. Rana, Y. Otani, W. Yu, T. Yu, G. E. W. Bauer, C. Back, G. S. Uhrig, O. Dobrovolskiy, B. Budinska, H. Qin, S. van Dijken, A. Chumak, A. Khitun, D. E. Nikonov, I. A. Young, B. W. Zingsem, M. Winklhofer
Summary: Magnonics is a burgeoning research field that focuses on utilizing spin waves to transmit, store, and process information, showing significant progress in the past decade. The key challenges include excitation of sub-100 nm wavelength magnons, manipulation on the nanoscale, and creation of sub-micrometre devices using low-Gilbert damping magnetic materials. Magnonics offers advantages such as lower energy consumption, easier integrability, compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity, and efficient tunability by various external stimuli.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Tom S. Seifert, Ulrike Martens, Florin Radu, Mirkow Ribow, Marco Berritta, Lukas Nadvornik, Ronald Starke, Tomas Jungwirth, Martin Wolf, Ilie Radu, Markus Muenzenberg, Peter M. Oppeneer, Georg Woltersdorf, Tobias Kampfrath
Summary: The anomalous Hall effect (AHE) remains operative from DC up to 40 THz in thin films of technologically relevant magnetic materials, with the large Drude scattering rate of metal thin films smearing out any sharp spectral features of the THz AHE. The intrinsic contribution dominates over the extrinsic mechanisms in the THz AHE for the Co32Fe68 sample, indicating promising potential for future THz spintronic devices operating reliably from DC to 40 Thz.
ADVANCED MATERIALS
(2021)
News Item
Physics, Multidisciplinary
Markus Munzenberg
Summary: Generating short-wavelength coherent spin waves that can travel at high speed over a long distance could potentially revolutionize data processing.
Article
Physics, Applied
Finn-Frederik Stiewe, Tristan Winkel, Yuta Sasaki, Tobias Tubandt, Tobias Kleinke, Christian Denker, Ulrike Martens, Nina Meyer, Tahereh Sadat Parvini, Shigemi Mizukami, Jakob Walowski, Markus Muenzenberg
Summary: We investigate the generation of local THz fields using spintronic THz emitters to improve the resolution for micrometer-sized imaging. By employing optical laser pulses as a pump, the THz field generation can be localized to the area of laser beam focusing. Through the use of scanning techniques and gold test patterns, we achieve sub-micrometer spatial resolution at the dimensions of the laser spot size.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
A. L. Chekhov, Y. Behovits, J. J. F. Heitz, C. Denker, D. A. Reiss, M. Wolf, M. Weinelt, P. W. Brouwer, M. Muenzenberg, T. Kampfrath
Summary: The ultrafast magnetization quenching of ferromagnetic iron following excitation by an optical versus terahertz pump pulse was studied. It was found that the MOKE signals exhibited an almost identical time evolution for both optical and terahertz pump pulses despite a significant difference in the number of excited electrons. Results were quantitatively explained using a nonthermal model based on quasielastic spin-flip scattering.
Review
Physics, Applied
Alexey Kimel, Anatoly Zvezdin, Sangeeta Sharma, Samuel Shallcross, Nuno de Sousa, Antonio Garcia-Martin, Georgeta Salvan, Jaroslav Hamrle, Ondrej Stejskal, Jeffrey McCord, Silvia Tacchi, Giovanni Carlotti, Pietro Gambardella, Gian Salis, Markus Muenzenberg, Martin Schultze, Vasily Temnov, Igor Bychkov, Leonid N. Kotov, Nicolo Maccaferri, Daria Ignatyeva, Vladimir Belotelov, Claire Donnelly, Aurelio Hierro Rodriguez, Iwao Matsuda, Thierry Ruchon, Mauro Fanciulli, Maurizio Sacchi, Chunhui Rita Du, Hailong Wang, N. Peter Armitage, Mathias Schubert, Vanya Darakchieva, Bilu Liu, Ziyang Huang, Baofu Ding, Andreas Berger, Paolo Vavassori
Summary: This article provides a comprehensive overview of recent developments, advances, and emerging research directions in the field of magneto-optics. It covers various applications of magneto-optical effects in different materials and spectral ranges. It serves as an important reference for emerging research directions in modern magneto-optics.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Finn-Frederik Stiewe, Tristan Winkel, Tobias Kleinke, Tobias Tubandt, Hauke Heyen, Lucas Vollroth, Ulrike Martens, Cai Mueller, Jeffrey McCord, Jakob Walowski, Markus Muenzenberg
Summary: In this study, we use THz radiation to determine the alignment of magnetic domains in a CoFeB layer. By generating THz pulses using fs laser pulses in magnetized CoFeB/Pt heterostructures based on spin currents, and detecting the radiation phase-sensitively using an LT-GaAs Auston switch, we are able to determine the magnetization alignment. Our scanning technique with motorized stages allows us to image two dimensional magnetic structures, and by using near-field imaging, we can enhance the spatial resolution. We prepare spintronic emitters of diverse geometric shapes and sizes to observe the formation of magnetization patterns, and demonstrate the influence of external magnetic fields on the alignment of emitted THz radiation. The combination of this method with THz range spectroscopic information makes it interesting for wider applications in probing high-resolution THz excitation in spin systems.
Article
Physics, Applied
Marcel Kohlmann, Christian Denker, Nikolai C. Passler, Jana Kredl, Martin Wolf, Markus Muenzenberg, Alexander Paarmann
Summary: In this study, we experimentally observed the enhancement of mid-infrared second-harmonic generation using grating-coupled surface phonon polaritons and discussed the design options for engineering the plasmon-phonon polariton hybridization. The polariton-enhanced effect in this geometry was found to be relatively low compared to other coupling methods.
APPLIED PHYSICS LETTERS
(2022)
Article
Multidisciplinary Sciences
Justyna Rychly-Gruszecka, Jakob Walowski, Christian Denker, Tobias Tubandt, Markus Muenzenberg, Jaroslaw W. Klos
Summary: In this study, the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals is investigated. The results show that the width of stripes and the width of gaps between them can affect the spin-wave frequencies by confining the spin waves inside the stripes and freeing the spin waves to a different extent on the edges of stripes. The frequency of the fundamental mode can be tuned by adjusting the geometrical parameters.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Multidisciplinary
Eva Schmoranzerova, Jozef Kimak, Richard Schlitz, Sebastian T. B. Goennenwein, Dominik Kriegner, Helena Reichlova, Zbynek Soban, Gerhard Jakob, Er-Jia Guo, Mathias Klaeui, Markus Muenzenberg, Petr Nemec, Tomas Ostatnicky
Summary: All-optical ferromagnetic resonance (AO-FMR) is used to detect micromagnetic parameters in yttrium iron garnet (YIG) thin films with a metallic capping layer (Au, Pt) by triggering magnetization precession through heating of the metallic layer with femtosecond laser pulses. The laser-induced precession corresponds to a uniform (Kittel) magnon mode, allowing for the measurement of local magnetic properties with a resolution determined by the laser spot size.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Applied
R. Rouzegar, A. L. Chekhov, Y. Behovits, B. R. Serrano, M. A. Syskaki, C. H. Lambert, D. Engel, U. Martens, M. Muenzenberg, M. Wolf, G. Jakob, M. Klaeui, T. S. Seifert, T. Kampfrath
Summary: In this work, we significantly enhance the performance of an optically pumped spintronic terahertz emitter (STE) by optimizing the photonic and thermal environment. The terahertz pulses generated using high-energy pump pulses exhibit high electric fields and fluences comparable to those of a state-of-the-art terahertz source based on optical rectification. The optimized STE design retains the advantages of the standard design, but without the power loss associated with LiNbO3 setups, making it a promising tool for nonlinear terahertz spectroscopy. The emitted terahertz pulse using low-energy laser pulses shows a 2-fold improvement in electric field and covers a wider spectrum.
PHYSICAL REVIEW APPLIED
(2023)
Article
Engineering, Electrical & Electronic
Neha Jha, Anand Pariyar, Tahereh Sadat Parvini, Christian Denker, Pavan K. Vardhanapu, Gonela Vijaykumar, Arne Ahrens, Tobias Meyer, Michael Seibt, Nicolae Atodiresei, Jagadeesh S. Moodera, Swadhin K. Mandal, Markus Muenzenberg
Summary: Delocalized carbon-based radical species with unpaired spin have been used to fabricate Cu-PLY- and ZnPLY-based organic magnetic tunnel junctions. These junctions show nonlinear and weakly temperature-dependent current-voltage characteristics, indicating tunneling as the dominant transport mechanism. Cu-PLY-based OMTJs exhibit significant magnetoresistance due to the formation of hybrid states at the metal-molecule interfaces called spinterface, and also show stable voltage-driven resistive switching.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
E. Schmoranzerova, T. Ostatnicky, J. Kimak, D. Kriegner, H. Reichlova, R. Schlitz, A. Badura, Z. Soban, M. Muenzenberg, G. Jakob, E-J Guo, M. Klaeui, P. Nemec
Summary: We observed a giant quadratic magneto-optical effect in a 50 nm thick YIG layer. Through theoretical and experimental methods, we quantified both linear and quadratic magneto-optical effects in the studied material. The quadratic magneto-optical signal in the thin YIG film exceeded the linear response, reaching values of 450 grads that are comparable with Heusler alloys or ferromagnetic semiconductors. This enhancement is attributed to antiferromagnetic coupling of two Fe sublattices. We also found that the choice of experimental conditions, particularly the wavelength, is crucial for optimizing the quadratic magneto-optical effect.
Article
Chemistry, Multidisciplinary
Leonid A. Shelukhin, Rashid R. Gareev, Vladyslav Zbarsky, Jakob Walowski, Markus Munzenberg, Nikolay A. Pertsev, Alexandra M. Kalashnikova
Summary: This study presents an experimental investigation of laser-induced magnetization dynamics in a CoFeB/MgO/CoFeB MTJ. The results show that a femtosecond laser pulse can induce magnetization precession in the thinner CoFeB layer and the precession frequency increases nonlinearly with increasing pump fluence. Additionally, the gradual quenching of interfacial magnetic anisotropy with increasing fluence is explained by laser-induced heating of the MTJ.
