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Pelliciari J, Lee S, Gilmore K, Li J, Gu Y, Barbour A, Jarrige I, Ahn CH, Walker FJ, Bisogni V. Tuning spin excitations in magnetic films by confinement. Nat Mater 2021; 20:188-193. [PMID: 33462465 DOI: 10.1038/s41563-020-00878-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Spin excitations of magnetic thin films are the founding element for magnetic devices in general. While spin dynamics have been extensively studied in bulk materials, the behaviour in mesoscopic films is less known due to experimental limitations. Here, we employ resonant inelastic X-ray scattering to investigate the spectrum of spin excitations in mesoscopic Fe films, from bulk-like films down to three unit cells. In bulk samples, we find isotropic, dispersive ferromagnons consistent with previous neutron scattering results for bulk single crystals. As the thickness is reduced, these ferromagnetic spin excitations renormalize to lower energies along the out-of-plane direction while retaining their dispersion in the in-plane direction. This thickness dependence is captured by simple Heisenberg model calculations accounting for the confinement in the out-of-plane direction through the loss of Fe bonds. Our findings highlight the effects of mesoscopic scaling on spin dynamics and identify thickness as a knob for fine tuning and controlling magnetic properties.
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Affiliation(s)
- Jonathan Pelliciari
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA.
| | - Sangjae Lee
- Department of Physics, Yale University, New Haven, CT, USA
| | - Keith Gilmore
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Jiemin Li
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Yanhong Gu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Andi Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Ignace Jarrige
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Charles H Ahn
- Department of Applied Physics, Yale University, New Haven, CT, USA
| | | | - Valentina Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA.
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Zingsem BW, Feggeler T, Terwey A, Ghaisari S, Spoddig D, Faivre D, Meckenstock R, Farle M, Winklhofer M. Biologically encoded magnonics. Nat Commun 2019; 10:4345. [PMID: 31554798 DOI: 10.1038/s41467-019-12219-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/06/2019] [Indexed: 11/29/2022] Open
Abstract
Spin wave logic circuits using quantum oscillations of spins (magnons) as carriers of information have been proposed for next generation computing with reduced energy demands and the benefit of easy parallelization. Current realizations of magnonic devices have micrometer sized patterns. Here we demonstrate the feasibility of biogenic nanoparticle chains as the first step to truly nanoscale magnonics at room temperature. Our measurements on magnetosome chains (ca 12 magnetite crystals with 35 nm particle size each), combined with micromagnetic simulations, show that the topology of the magnon bands, namely anisotropy, band deformation, and band gaps are determined by local arrangement and orientation of particles, which in turn depends on the genotype of the bacteria. Our biomagnonic approach offers the exciting prospect of genetically engineering magnonic quantum states in nanoconfined geometries. By connecting mutants of magnetotactic bacteria with different arrangements of magnetite crystals, novel architectures for magnonic computing may be (self-) assembled. The capability to engineer magnon states in confined geometries is vital to future nano-magnonics. Here the authors demonstrate that the topology of the magnon bands is determined by the local arrangement and orientation of nanoparticles and can be controlled by the genotype of magnetotactic bacteria.
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Mohseni M, Verba R, Brächer T, Wang Q, Bozhko DA, Hillebrands B, Pirro P. Backscattering Immunity of Dipole-Exchange Magnetostatic Surface Spin Waves. Phys Rev Lett 2019; 122:197201. [PMID: 31144927 DOI: 10.1103/physrevlett.122.197201] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Indexed: 06/09/2023]
Abstract
The existence of backscattering-immune spin-wave modes is demonstrated in magnetic thin films of nanoscale thickness. Our results reveal that chiral magnetostatic surface waves (CMSSWs), which propagate perpendicular to the magnetization direction in an in-plane magnetized thin film, are robust against backscattering from surface defects. CMSSWs are protected against various types of surface inhomogeneities and defects as long as their frequency lies inside the gap of the volume modes. Our explanation is independent of the topology of the modes and predicts that this robustness is a consequence of symmetry breaking of the dynamic magnetic fields of CMSSWs due to the off-diagonal part of the dipolar interaction tensor, which is present both for long- (dipole-dominated) and short-wavelength (exchange-dominated) spin waves. Micromagnetic simulations confirm the robust character of the CMSSWs. Our results open a new direction in designing highly efficient magnonic logic elements and devices employing CMSSWs in nanoscale thin films.
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Affiliation(s)
- M Mohseni
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - R Verba
- Institute of Magnetism, Kyiv 03680, Ukraine
| | - T Brächer
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Q Wang
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - D A Bozhko
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - B Hillebrands
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - P Pirro
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
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Brächer T, Fabre M, Meyer T, Fischer T, Auffret S, Boulle O, Ebels U, Pirro P, Gaudin G. Detection of Short-Waved Spin Waves in Individual Microscopic Spin-Wave Waveguides Using the Inverse Spin Hall Effect. Nano Lett 2017; 17:7234-7241. [PMID: 29148808 DOI: 10.1021/acs.nanolett.7b02458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The miniaturization of complementary metal-oxide-semiconductor (CMOS) devices becomes increasingly difficult due to fundamental limitations and the increase of leakage currents. Large research efforts are devoted to find alternative concepts that allow for a larger data-density and lower power consumption than conventional semiconductor approaches. Spin waves have been identified as a potential technology that can complement and outperform CMOS in complex logic applications, profiting from the fact that these waves enable wave computing on the nanoscale. The practical application of spin waves, however, requires the demonstration of scalable, CMOS compatible spin-wave detection schemes in material systems compatible with standard spintronics as well as semiconductor circuitry. Here, we report on the wave-vector independent detection of short-waved spin waves with wavelengths down to 150 nm by the inverse spin Hall effect in spin-wave waveguides made from ultrathin Ta/Co8Fe72B20/MgO. These findings open up the path for miniaturized scalable interconnects between spin waves and CMOS and the use of ultrathin films made from standard spintronic materials in magnonics.
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Affiliation(s)
- T Brächer
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
| | - M Fabre
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
| | - T Meyer
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern , 67663 Kaiserslautern, Germany
| | - T Fischer
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern , 67663 Kaiserslautern, Germany
- Graduate School Materials Science in Mainz , Gottlieb-Daimler-Strasse 47, D-67663 Kaiserslautern, Germany
| | - S Auffret
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
| | - O Boulle
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
| | - U Ebels
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
| | - P Pirro
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern , 67663 Kaiserslautern, Germany
| | - G Gaudin
- University Grenoble Alpes, CEA, CNRS, Grenoble INP, INAC, SPINTEC , F-38000 Grenoble, France
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