Spatially resolved GHz magnetization dynamics of a magnetite nano-particle chain inside a magnetotactic bacterium

Feggeler, Thomas; Meckenstock, R.; Spoddig, D.; Zingsem, Benjamin; Ohldag, Hendrik; Wende, Heiko; Farle, Michael; Winklhofer, Michael; Ollefs, Katharina

doi:10.1103/physrevresearch.3.033036

Cited by 7 publications

(7 citation statements)

References 36 publications

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“…cubic magnetocrystalline anisotropy [39]. For the simulation considering the imperfections in the stoichiometry of the Fe 3 O 4 [43] and in accordance with earlier studies [25], the saturation magnetization and the first order cubic magnetocrystalline anisotropy constant were set to M Sat = 465 kA m −1 , and [44], respectively. A simulation grid of 200 × 200 × 12 cells with a cell size of (5 nm) 3 was defined with an exchange stiffness A = 1.32 × 10 −11 J m −1 [45].…”

Section: Details Of Experiments and Simulationmentioning

confidence: 99%

“…Besides these common techniques to characterize magnetization and its dynamics, time-resolved scanning transmission x-ray microscopy (TR-STXM), offering sub-50 nm spatially resolved and element-specific sampling of gigahertz dynamics up to tens of GHz [21][22][23], has been used to measure uniform and non-uniform dynamic excitations within nano-and microstructured samples [21][22][23][24][25][26][27][28][29][30]. The technique measures dynamic magnetic excitations in the linear regime incorporating the x-ray magnetic circular dichroism effect [31][32][33] as contrast mechanism, enabling a phase resolved sampling of the magnetization dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Spatially-resolved dynamic sampling of different phasic magnetic resonances of nanoparticle ensembles in a magnetotactic bacterium Magnetospirillum magnetotacticum

et al. 2023

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Nanoscaled magnetic particle ensembles are promising building blocks for realising magnon based binary logic. Element-specific real-space monitoring of magnetic resonance modes with sampling rates in the GHz regime is imperative for the experimental verification of future complex magnonic devices. Here we present the observation of different phasic magnetic resonance modes using the element-specific technique of Time-Resolved Scanning Transmission X-ray Microscopy (TR-STXM) within a chain of dipolarly coupled Fe3O4 nanoparticles (40-50 nm particle size) inside a single cell of a magnetotactic bacterium \textit{Magnetospirillum Magnetotacticum}. The particles are probed with 25~nm resolution at the Fe L3 X-ray absorption edge in response to a microwave excitation of 4.07 GHz. A plethora of resonance modes is observed within multiple particle segments oscillating in- and out-of-phase, well resembled by micromagnetic simulations.

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Section: Details Of Experiments and Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatially-resolved dynamic sampling of different phasic magnetic resonances of nanoparticle ensembles in a magnetotactic bacterium Magnetospirillum magnetotacticum

et al. 2023

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“…In this study Scanning Transmission X-ray Microscopy detected FMR (STXM-FMR) 16 has been used, offering temporal sampling down to 17 ps and nominal sub 50 nm lateral resolution in transverse XFMR geometry with a continuous wave excitation of the sample [16][17][18][19][20][21] . Uniform and non uniform resonant responses on the micro- 22,23 and sub 50 nm nanometer 24 scale have been monitored and analysed. Here we investigate resonant excitations of a bilayered microstructure consisting of a Cobalt (Co) stripe deposited on a Permalloy (Py) disk with element specificity.…”

Section: Elementmentioning

confidence: 99%

Element-specific visualization of dynamic magnetic coupling in a Co/Py bilayer microstructure

Feggeler

Meckenstock

Spoddig

et al. 2022

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We present the element-specific and time resolved visualization of uniform ferromagnetic resonance excitations of a Permalloy (Py) disk–Cobalt (Co) stripe bilayer microstructure. The transverse high frequency component of the resonantly excited magnetization is sampled in the ps regime by a combination of ferromagnetic resonance (FMR) and scanning transmission X-ray microscopy (STXM-FMR) recording snapshots of the local magnetization precession of Py and Co with nanometer spatial resolution. The approach allows us to individually image the resonant dynamic response of each element, and we find that angular momentum is transferred from the Py disk to the Co stripe and vice versa at their respective resonances. The integral (cavity) FMR spectrum of our sample shows an unexpected additional third resonance. This resonance is observed in the STXM-FMR experiments as well. Our microscopic findings suggest that it is governed by magnetic exchange between Py and Co, showing for the Co stripe a difference in relative phase of the magnetization due to stray field influence.

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“…Magnetotactic bacteria are microorganisms that have the ability to synthesize internally membrane-enclosed single-domain magnetic nanoparticles called magnetosomes. Within the bacterium, magnetosomes are aligned, forming an internal magnetic chain which behaves as a large permanent magnetic dipole causing their orientation along the geomagnetic field lines. − Previous works have demonstrated the superiority of STXM-XMCD over XPEEM for magnetic imaging of intracellular magnetosomes. − …”

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confidence: 99%

“… 32 − 36 Previous works have demonstrated the superiority of STXM-XMCD over XPEEM for magnetic imaging of intracellular magnetosomes. 37 − 42 …”

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confidence: 99%

Magnetic Anisotropy of Individual Nanomagnets Embedded in Biological Systems Determined by Axi-asymmetric X-ray Transmission Microscopy

et al. 2022

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Over the past few years, the use of nanomagnets in biomedical applications has increased. Among others, magnetic nanostructures can be used as diagnostic and therapeutic agents in cardiovascular diseases, to locally destroy cancer cells, to deliver drugs at specific positions, and to guide (and track) stem cells to damaged body locations in regenerative medicine and tissue engineering. All these applications rely on the magnetic properties of the nanomagnets which are mostly determined by their magnetic anisotropy. Despite its importance, the magnetic anisotropy of the individual magnetic nanostructures is unknown. Currently available magnetic sensitive microscopic methods are either limited in spatial resolution or in magnetic field strength or, more relevant, do not allow one to measure magnetic signals of nanomagnets embedded in biological systems. Hence, the use of nanomagnets in biomedical applications must rely on mean values obtained after averaging samples containing thousands of dissimilar entities. Here we present a hybrid experimental/theoretical method capable of working out the magnetic anisotropy constant and the magnetic easy axis of individual magnetic nanostructures embedded in biological systems. The method combines scanning transmission X-ray microscopy using an axi-asymmetric magnetic field with theoretical simulations based on the Stoner–Wohlfarth model. The validity of the method is demonstrated by determining the magnetic anisotropy constant and magnetic easy axis direction of 15 intracellular magnetite nanoparticles (50 nm in size) biosynthesized inside a magnetotactic bacterium.

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Spatially resolved GHz magnetization dynamics of a magnetite nano-particle chain inside a magnetotactic bacterium

Cited by 7 publications

References 36 publications

Spatially-resolved dynamic sampling of different phasic magnetic resonances of nanoparticle ensembles in a magnetotactic bacterium Magnetospirillum magnetotacticum

Spatially-resolved dynamic sampling of different phasic magnetic resonances of nanoparticle ensembles in a magnetotactic bacterium Magnetospirillum magnetotacticum

Element-specific visualization of dynamic magnetic coupling in a Co/Py bilayer microstructure

Magnetic Anisotropy of Individual Nanomagnets Embedded in Biological Systems Determined by Axi-asymmetric X-ray Transmission Microscopy

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