Recent advances in Lorentz microscopy

Phatak, Charudatta; Petford‐Long, Amanda K.; Graef, Marc De

doi:10.1016/j.cossms.2016.01.002

Cited by 63 publications

(35 citation statements)

References 56 publications

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“…LTEM provides information on the stray field magnetization with spatial resolution of a few nanometers and can hence be applied to individual particles with sizes as small as a few nanometers. [ 97 ] Electron holography provides higher spatial resolution and is sensitive to the entire nanoparticle spin configuration and has been applied to the magnetic interparticle coupling in arrangements of nanoparticles. [ 111 ] On the individual nanoparticle level, high‐resolution magnetic maps of individual Fe nanocubes have been generated to reveal the size‐induced transition between vortex ( Figure a–c) and single‐domain states (Figure 5d–f) within the nanoparticles.…”

Section: Defect‐induced Spin Disorder In Iron Oxide Nanoparticlesmentioning

confidence: 99%

Embracing Defects and Disorder in Magnetic Nanoparticles

2021

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Iron oxide nanoparticles have tremendous scientific and technological potential in a broad range of technologies, from energy applications to biomedicine. To improve their performance, single‐crystalline and defect‐free nanoparticles have thus far been aspired. However, in several recent studies, defect‐rich nanoparticles outperform their defect‐free counterparts in magnetic hyperthermia and magnetic particle imaging (MPI). Here, an overview on the state‐of‐the‐art of design and characterization of defects and resulting spin disorder in magnetic nanoparticles is presented with a focus on iron oxide nanoparticles. The beneficial impact of defects and disorder on intracellular magnetic hyperthermia performance of magnetic nanoparticles for drug delivery and cancer therapy is emphasized. Defect‐engineering in iron oxide nanoparticles emerges to become an alternative approach to tailor their magnetic properties for biomedicine, as it is already common practice in established systems such as semiconductors and emerging fields including perovskite solar cells. Finally, perspectives and thoughts are given on how to deliberately induce defects in iron oxide nanoparticles and their potential implications for magnetic tracers to monitor cell therapy and immunotherapy by MPI.

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Section: Defect‐induced Spin Disorder In Iron Oxide Nanoparticlesmentioning

confidence: 99%

Embracing Defects and Disorder in Magnetic Nanoparticles

2021

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“…For example, Lorentz microscopy offers extremely high spatial resolution (sub-5 nm) but requires electron-transparent samples and temporal resolution remains challenging. [7] Beamline techniques such as magnetic transmission X-ray microscopy (M-TXM) [8,9] and X-ray magnetic circular dichroism photoelectron emission microscopy (XMCD-PEEM) [10,11] combine high spatial resolution (sub-10 nm [12,13] for M-TXM, sub-50 nm for XMCD-PEEM [14,15] ) with ultrafast proportional to the rate constant k 2 , respectively. In the case of an MPL sample with randomly oriented molecules, three of the nine possible 1 (TT) states possess singlet character when no external magnetic field is present.…”

Section: Introductionmentioning

confidence: 99%

Wide Field Magnetic Luminescence Imaging

Hodges

Grell

Morley

et al. 2017

Adv Funct Materials

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This study demonstrates how magnetic-field-dependent luminescence from organic films can be used to image the magnetic configuration of an underlying sample. The organic semiconductors tetracene and rubrene exhibit singlet exciton fission, which is a process sensitive to magnetic fields. Here, thin films of these materials were characterized using photoluminescence spectrometry, atomic force microscopy, and photoluminescence magnetometry. The luminescence from these substrate-bound thin films is imaged to reveal the magnetic configuration of underlying Nd-Fe-B magnets. The tendency of rubrene to form amorphous films and produce large changes in photoluminescence under an applied magnetic field makes it more appropriate for magnetic field imaging than tetracene. This demonstration can be extended in the future to allow simple microscopic imaging of magnetic structure.

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“…We used the following parameters: λ = 2.51 pm, t' = 200 nm, C s = 8000 mm and α = 10 µrad (refs. 51,52 ).…”

Section: Methodsmentioning

confidence: 99%

Observation of domain wall bimerons in chiral magnets

Nagase

Yasui

et al. 2021

Nat Commun

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Topological defects embedded in or combined with domain walls have been proposed in various systems, some of which are referred to as domain wall skyrmions or domain wall bimerons. However, the experimental observation of such topological defects remains an ongoing challenge. Here, using Lorentz transmission electron microscopy, we report the experimental discovery of domain wall bimerons in chiral magnet Co-Zn-Mn(110) thin films. By applying a magnetic field, multidomain structures develop, and simultaneously, chained or isolated bimerons arise as the localized state between the domains with the opposite in-plane components of net magnetization. The multidomain formation is attributed to magnetic anisotropy and dipolar interaction, and domain wall bimerons are stabilized by the Dzyaloshinskii-Moriya interaction. In addition, micromagnetic simulations show that domain wall bimerons appear for a wide range of conditions in chiral magnets with cubic magnetic anisotropy. Our results promote further study in various fields of physics.

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Recent advances in Lorentz microscopy

Cited by 63 publications

References 56 publications

Embracing Defects and Disorder in Magnetic Nanoparticles

Embracing Defects and Disorder in Magnetic Nanoparticles

Wide Field Magnetic Luminescence Imaging

Observation of domain wall bimerons in chiral magnets

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