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Li Y, Wang X, Ma L. Instability of skyrmion lattice under microwave magnetic field due to single- qhelimagnetic excitation mode. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:105801. [PMID: 36538827 DOI: 10.1088/1361-648x/acad56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Composed of the three spiral magnetic vectors, the structure of skyrmion lattice (SkL) can be destructed by spin excitations in possibly two ways: one is to make decoherence of all the helices through the phase change of a certain spiral magnetic vector, and the other is to inhibit one or two spiral components while enhancing the others so that it becomes a magnetic structure of single or double magnetic vectors. Here, we present a micromagnetic study on the spin excitations of a two-dimensional SkL under the in-plane microwave magnetic field. By calculating the parameters describing the in-plane spin excitations mode, we find that the spin configuration tends to be an enhanced single-vector spiral magnetic structure due to the excitation modes under some specific frequencies so that the SkL will collapse to the topologically trivial state. Our results help to form a deeper understanding of the spin excitation in SkL under an ac magnetic field.
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Affiliation(s)
- Yang Li
- Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, People's Republic of China
| | - Xuan Wang
- Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, People's Republic of China
| | - Leikai Ma
- Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730030, People's Republic of China
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Huang H, Shuai M, Yang Y, Song R, Liao Y, Yin L, Shen J. Cryogen free spin polarized scanning tunneling microscopy and magnetic exchange force microscopy with extremely low noise. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:073703. [PMID: 35922334 DOI: 10.1063/5.0095271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
Spin polarized scanning tunneling microscopy (SP-STM) and magnetic exchange force microscopy (MExFM) are powerful tools to characterize spin structure at the atomic scale. For low temperature measurements, liquid helium cooling is commonly used, which has the advantage of generating low noise but has the disadvantage of having difficulties in carrying out measurements with long durations at low temperatures and measurements with a wide temperature range. The situation is just reversed for cryogen-free STM, where the mechanical vibration of the refrigerator becomes a major challenge. In this work, we have successfully built a cryogen-free system with both SP-STM and MExFM capabilities, which can be operated under a 9 T magnetic field provided by a cryogen-free superconducting magnet and in a wide temperature range between 1.4 and 300 K. With the help of our specially designed vibration isolation system, the noise is reduced to an extremely low level of 0.7 pm. The Fe/Ir(111) magnetic skyrmion lattice is used to demonstrate the technical novelties of our cryogen-free system.
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Affiliation(s)
- Haiming Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Mingming Shuai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yulong Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Rui Song
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yanghui Liao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Lifeng Yin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Jian Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
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Berganza E, Jaafar M, Fernandez-Roldan JA, Goiriena-Goikoetxea M, Pablo-Navarro J, García-Arribas A, Guslienko K, Magén C, De Teresa JM, Chubykalo-Fesenko O, Asenjo A. Half-hedgehog spin textures in sub-100 nm soft magnetic nanodots. NANOSCALE 2020; 12:18646-18653. [PMID: 32584341 DOI: 10.1039/d0nr02173c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Topologically non-trivial structures such as magnetic skyrmions are nanometric spin textures of outstanding potential for spintronic applications due to their unique features. It is well known that Néel skyrmions of definite chirality are stabilized by the Dzyaloshinskii-Moriya exchange interaction (DMI) in bulk non-centrosymmetric materials or ultrathin films with strong spin-orbit coupling at the interface. In this work, we show that soft magnetic (permalloy) hemispherical nanodots are able to host three-dimensional chiral structures (half-hedgehog spin textures) with non-zero tropological charge. They are observed at room temperature, in absence of DMI interaction and they can be further stabilized by the magnetic field arising from the Magnetic Force Microscopy probe. Micromagnetic simulations corroborate the experimental data. Our work implies the existence of a new degree of freedom to create and manipulate complex 3D spin-textures in soft magnetic nanodots and opens up future possibilities to explore their magnetization dynamics.
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Affiliation(s)
- Eider Berganza
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain
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Seifert TS, Kovarik S, Juraschek DM, Spaldin NA, Gambardella P, Stepanow S. Longitudinal and transverse electron paramagnetic resonance in a scanning tunneling microscope. SCIENCE ADVANCES 2020; 6:eabc5511. [PMID: 32998882 PMCID: PMC7527223 DOI: 10.1126/sciadv.abc5511] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy is widely used to characterize paramagnetic complexes. Recently, EPR combined with scanning tunneling microscopy (STM) achieved single-spin sensitivity with sub-angstrom spatial resolution. The excitation mechanism of EPR in STM, however, is broadly debated, raising concerns about widespread application of this technique. We present an extensive experimental study and modeling of EPR-STM of Fe and hydrogenated Ti atoms on a MgO surface. Our results support a piezoelectric coupling mechanism, in which the EPR species oscillate adiabatically in the inhomogeneous magnetic field of the STM tip. An analysis based on Bloch equations combined with atomic-multiplet calculations identifies different EPR driving forces. Specifically, transverse magnetic field gradients drive the spin-1/2 hydrogenated Ti, whereas longitudinal magnetic field gradients drive the spin-2 Fe. Also, our results highlight the potential of piezoelectric coupling to induce electric dipole moments, thereby broadening the scope of EPR-STM to nonpolar species and nonlinear excitation schemes.
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Affiliation(s)
- Tom S Seifert
- Department of Materials, ETH Zürich, 8093 Zürich, Switzerland.
| | - Stepan Kovarik
- Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Dominik M Juraschek
- Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Malavolti L, McMurtrie G, Rolf-Pissarczyk S, Yan S, Burgess JAJ, Loth S. Minimally invasive spin sensing with scanning tunneling microscopy. NANOSCALE 2020; 12:11619-11626. [PMID: 32435779 DOI: 10.1039/c9nr10252c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Minimizing the invasiveness of scanning tunneling measurements is paramount for observation of the magnetic properties of unperturbed atomic-scale objects. We show that the invasiveness of STM inspection on few-atom spin systems can be drastically reduced by means of a remote detection scheme, which makes use of a sensor spin weakly coupled to the sensed object. By comparing direct and remote measurements we identify the relevant perturbations caused by the local probe. For direct inspection we find that tunneling electrons strongly perturb the investigated object even for currents as low as 3 pA. Electrons injected into the sensor spin induce perturbations with much reduced probability. The sensing scheme uses standard differential conductance measurements, and is decoupled both by its non-local nature, and by dynamic decoupling due to the significantly different time scales at which the sensor and sensed object evolve. The latter makes it possible to effectively remove static interactions between the sensed object and the spin sensor while still allowing the spin sensing. In this way we achieve measurements with a reduction in perturbative effects of up to 100 times relative to direct scanning tunneling measurements, which enables minimally invasive measurements of a few-atom magnet's fragile spin states with STM.
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Affiliation(s)
- Luigi Malavolti
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569 Stuttgart, Germany. and Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Gregory McMurtrie
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569 Stuttgart, Germany. and Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Steffen Rolf-Pissarczyk
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Shichao Yan
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany and School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jacob A J Burgess
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany and Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Sebastian Loth
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569 Stuttgart, Germany. and Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany and Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
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Hauptmann N, Haldar S, Hung TC, Jolie W, Gutzeit M, Wegner D, Heinze S, Khajetoorians AA. Quantifying exchange forces of a spin spiral on the atomic scale. Nat Commun 2020; 11:1197. [PMID: 32139680 PMCID: PMC7057993 DOI: 10.1038/s41467-020-15024-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 02/13/2020] [Indexed: 11/09/2022] Open
Abstract
The large interest in chiral magnetic structures for realization of nanoscale magnetic storage or logic devices has necessitated methods which can quantify magnetic interactions at the atomic scale. To overcome the limitations of the typically used current-based sensing of atomic-scale exchange interactions, a force-based detection scheme is highly advantageous. Here, we quantify the atomic-scale exchange force field between a ferromagnetic tip and a cycloidal spin spiral using our developed combination of current and exchange force detection. Compared to the surprisingly weak spin polarization, the exchange force field is more sensitive to atomic-scale variations in the magnetization. First-principles calculations reveal that the measured atomic-scale variations in the exchange force originate from different contributions of direct and indirect (Zener type) exchange mechanisms, depending on the chemical tip termination. Our work opens the perspective of quantifying different exchange mechanisms of chiral magnetic structures with atomic-scale precision using 3D magnetic exchange force field measurements.
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Affiliation(s)
- Nadine Hauptmann
- Institute for Molecules and Materials, Radboud University, 6525 AJ, Nijmegen, Netherlands.
| | - Soumyajyoti Haldar
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität, Kiel, Germany
| | - Tzu-Chao Hung
- Institute for Molecules and Materials, Radboud University, 6525 AJ, Nijmegen, Netherlands
| | - Wouter Jolie
- Institute for Molecules and Materials, Radboud University, 6525 AJ, Nijmegen, Netherlands
| | - Mara Gutzeit
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität, Kiel, Germany
| | - Daniel Wegner
- Institute for Molecules and Materials, Radboud University, 6525 AJ, Nijmegen, Netherlands
| | - Stefan Heinze
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität, Kiel, Germany
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Zeng J, Darvishzadeh-Varcheie M, Albooyeh M, Rajaei M, Kamandi M, Veysi M, Potma EO, Capolino F, Wickramasinghe HK. Exclusive Magnetic Excitation Enabled by Structured Light Illumination in a Nanoscale Mie Resonator. ACS NANO 2018; 12:12159-12168. [PMID: 30516951 DOI: 10.1021/acsnano.8b05778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Recent work has shown that optical magnetism, generally considered a challenging light-matter interaction, can be significant at the nanoscale. In particular, the dielectric nanostructures that support magnetic Mie resonances are low-loss and versatile optical magnetic elements that can effectively manipulate the magnetic field of light. However, the narrow magnetic resonance band of dielectric Mie resonators is often overshadowed by the electric response, which prohibits the use of such nanoresonators as efficient magnetic nanoantennas. Here, we design and fabricate a silicon (Si) truncated cone magnetic Mie resonator at visible frequencies and excite the magnetic mode exclusively by a tightly focused azimuthally polarized beam. We use photoinduced force microscopy to experimentally characterize the local electric near-field distribution in the immediate vicinity of the Si truncated cone at the nanoscale and then create an analytical model of such structure that exhibits a matching electric field distribution. We use this model to interpret the PiFM measurement that visualizes the electric near-field profile of the Si truncated cone with a superior signal-to-noise ratio and infer the magnetic response of the Si truncated cone at the beam singularity. Finally, we perform a multipole analysis to quantitatively present the dominance of the magnetic dipole moment contribution compared to other multipole contributions into the total scattered power of the proposed structure. This work demonstrates the excellent efficiency and simplicity of our method of using Si truncated cone structure under APB illumination compared to other approaches to achieve dominant magnetic excitations.
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Tserkovnyak Y, Xiao J. Energy Storage via Topological Spin Textures. PHYSICAL REVIEW LETTERS 2018; 121:127701. [PMID: 30296130 DOI: 10.1103/physrevlett.121.127701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/23/2018] [Indexed: 06/08/2023]
Abstract
We formulate an energy-storage concept based on the free energy associated with metastable magnetic configurations. Despite the active magnetic region of the battery being electrically insulating, it can sustain effective hydrodynamics of spin textures, whose conservation law is governed by topology. To illustrate the key physics and potential functionality, we focus here on the simplest quasi-one-dimensional case of planar winding of the magnetic order parameter. The energy is stored in the metastable winding number, which can be injected electrically by an appropriately tailored spin torque. Because of the nonvolatility and the endurance of magnetic systems, the injected energy can be stored essentially indefinitely, with the topological charge cycles that do not degrade over time.
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Affiliation(s)
- Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Jiang Xiao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronics Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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