Hydrogen-plasma-induced magnetocrystalline anisotropy ordering in self-assembled magnetic nanoparticle monolayers

Self-assembled two-dimensional arrays of either 14 nm hcp-Co or 6 nm ε-Co particle components were treated by hydrogen plasma for various exposure times. A change of hysteretic sample behavior depending on the treatment duration is reported, which can be divided in two time scales: oxygen reduction increases the particle magnetization during the first 20 min, which is followed by an alteration of the magnetic response shape. The latter depends on the respective particle species. Based on the Landau–Lifshitz equations for a discrete set of magnetic moments, we propose a model that relates the change of the hysteresis loops to a dipole-driven ordering of the magnetocrystalline easy axes within the particle plane due to the high spatial aspect ratio of the system.

Download Full-text

Heating ability of magnetic nanoparticles with cubic and combined anisotropy

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.10.29 ◽

2019 ◽

Vol 10 ◽

pp. 305-314 ◽

Cited By ~ 13

Author(s):

Nikolai A Usov ◽

Mikhail S Nesmeyanov ◽

Elizaveta M Gubanova ◽

Natalia B Epshtein

Keyword(s):

Magnetite Nanoparticles ◽

Magnetic Nanoparticle ◽

Specific Absorption Rate ◽

Magnetic Moments ◽

Low Frequency ◽

Hysteresis Loops ◽

Dipole Interaction ◽

Thermal Fluctuations ◽

Fractal Clusters ◽

Cubic Anisotropy

The low frequency hysteresis loops and specific absorption rate (SAR) of assemblies of magnetite nanoparticles with cubic anisotropy are calculated in the diameter range of D = 20–60 nm taking into account both thermal fluctuations of the particle magnetic moments and strong magneto–dipole interaction in assemblies of fractal-like clusters of nanoparticles. Similar calculations are also performed for assemblies of slightly elongated magnetite nanoparticles having combined magnetic anisotropy. A substantial dependence of the SAR on the nanoparticle diameter is obtained for all cases investigated. Due to the influence of the magneto–dipole interaction, the SAR of fractal clusters of nanoparticles decreases considerably in comparison with that for weakly interacting nanoparticles. However, the ability of magnetic nanoparticle assemblies to generate heat can be improved if the nanoparticles are covered by nonmagnetic shells of appreciable thickness.

Download Full-text

Template-Free Self-Assembly of Two-Dimensional Polymers into Nano/Microstructured Materials

Molecules ◽

10.3390/molecules26113310 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3310

Author(s):

Shengda Liu ◽

Jiayun Xu ◽

Xiumei Li ◽

Tengfei Yan ◽

Shuangjiang Yu ◽

...

Keyword(s):

Self Assembly ◽

Recent Progress ◽

Two Dimensional ◽

Subsequent Removal ◽

The Past ◽

2D Polymers ◽

Template Free ◽

Self Assembled ◽

The Relationship ◽

Polymer Tubes

In the past few decades, enormous efforts have been made to synthesize covalent polymer nano/microstructured materials with specific morphologies, due to the relationship between their structures and functions. Up to now, the formation of most of these structures often requires either templates or preorganization in order to construct a specific structure before, and then the subsequent removal of previous templates to form a desired structure, on account of the lack of “self-error-correcting” properties of reversible interactions in polymers. The above processes are time-consuming and tedious. A template-free, self-assembled strategy as a “bottom-up” route to fabricate well-defined nano/microstructures remains a challenge. Herein, we introduce the recent progress in template-free, self-assembled nano/microstructures formed by covalent two-dimensional (2D) polymers, such as polymer capsules, polymer films, polymer tubes and polymer rings.

Download Full-text

Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain

ACS Applied Materials & Interfaces ◽

10.1021/acsami.6b03773 ◽

2016 ◽

Vol 8 (26) ◽

pp. 16845-16851 ◽

Cited By ~ 14

Author(s):

Wenrui Zhang ◽

Mingtao Li ◽

Aiping Chen ◽

Leigang Li ◽

Yuanyuan Zhu ◽

...

Keyword(s):

Two Dimensional ◽

Layered Oxide ◽

Layer Stacking ◽

Interfacial Strain ◽

Self Assembled ◽

Self Assembled Layer

Download Full-text

Two-dimensional optical scanner with large angular rotation realized by self-assembled micro-elevator

1998 IEEE/LEOS Summer Topical Meeting. Digest. Broadband Optical Networks and Technologies: An Emerging Reality. Optical MEMS. Smart Pixels. Organic Optics and Optoelectronics (Cat. No.98TH8369) ◽

10.1109/leosst.1998.689857 ◽

2002 ◽

Cited By ~ 11

Author(s):

L. Fan ◽

M.C. Wu

Keyword(s):

Two Dimensional ◽

Angular Rotation ◽

Optical Scanner ◽

Self Assembled

Download Full-text

Investigation on the Origin of Magnetization in Plastically Deformed NI51TI49 Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.743.13 ◽

2017 ◽

Vol 743 ◽

pp. 13-18

Author(s):

Anna Drozdova ◽

Alexander Nyavro ◽

Lyudmila Kveglis

Keyword(s):

Crystal Lattice ◽

Magnetic Moments ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Lattice Curvature ◽

Electron States ◽

Large Atom ◽

Transmission Electron ◽

Large Distortion ◽

Density Of Electron States

The article deals with the investigation of structure and magnetic properties of plastically deformed Ni51Ti49 alloy. The magnetic hysteresis loops confirm the presence of ferromagnetic properties in the alloy. The transmission electron microscopy (TEM) detects the appearance of lenticular crystals with bending contours which indicate the large distortion of the crystal lattice. The crystal lattice curvature occurs due to the large atom displacement. As a result, icosahedral clusters with the Frank-Kasper (FK) structure can be formed. The spin-polarized density of electron states and the magnetic moments for both non-deformed (near-spherical structure) and deformed (elongated by 5% along the Z-axis) Ni7Ti5 (FK-12), Ni8Ti5 (FK-13), and Ni10Ti6 (FK-16) clusters are calculated for the explanation of possibility of magnetization appearance in Ni51Ti49 alloy. The calculations show the increase in the magnetic moments for the deformed clusters. The calculated spectra demonstrate the high density of electron states near the Fermi level which is a characteristic feature of ferromagnetic alloys.

Download Full-text

Self-assembled two-dimensional nanoporous molecular arrays and photoinduced polymerization of 4-bromo-4′-hydroxybiphenyl on Ag(111)

The Journal of Chemical Physics ◽

10.1063/1.4906116 ◽

2015 ◽

Vol 142 (10) ◽

pp. 101902 ◽

Cited By ~ 14

Author(s):

Qian Shen ◽

Jing Hui He ◽

Jia Lin Zhang ◽

Kai Wu ◽

Guo Qin Xu ◽

...

Keyword(s):

Two Dimensional ◽

Photoinduced Polymerization ◽

Self Assembled

Download Full-text

Intriguing Strain-Governed Magnetic Phase Transitions in 2D Vanadium Porphyrin Sheet

Physical Chemistry Chemical Physics ◽

10.1039/d1cp04597k ◽

2022 ◽

Author(s):

Qi Wang ◽

Zhilu Zhang ◽

Hai-Cai Huang ◽

Xinyu song ◽

Yuxiang Bu

Keyword(s):

Magnetic Properties ◽

Phase Transitions ◽

Magnetic Phase ◽

2D Materials ◽

Magnetic Phase Transitions ◽

Strain Effect ◽

Magnetic Response ◽

Two Dimensional ◽

Spintronic Devices ◽

Electronic And Magnetic Properties

The strain effect on the magnetic response of the 2D materials as spintronic devices are always important in actual applications. Due to the intriguing electronic and magnetic properties of two-dimensional...

Download Full-text

Square-grid coordination networks of (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) in its clathrate with two guest molecules of 1,2-dichlorobenzene: supramolecular isomerism of the porphyrin self-assembly

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s0108270109005691 ◽

2009 ◽

Vol 65 (3) ◽

pp. m139-m142 ◽

Cited By ~ 10

Author(s):

Rajesh Koner ◽

Israel Goldberg

Keyword(s):

Self Assembly ◽

Metal Ion ◽

Three Dimensional ◽

Two Dimensional ◽

Coordination Networks ◽

Guest Molecules ◽

Square Grid ◽

Supramolecular Isomerism ◽

Self Assembled ◽

Solvent Molecules

The title compound, (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) 1,2-dichlorobenzene disolvate, [Zn(C40H24N8)]·2C6H4Cl2, contains a clathrate-type structure. It is composed of two-dimensional square-grid coordination networks of the self-assembled porphyrin moiety, which are stacked one on top of the other in a parallel manner. The interporphyrin cavities of the overlapping networks combine into channel voids accommodated by the dichlorobenzene solvent. Molecules of the porphyrin complex are located on crystallographic inversion centres. The observed two-dimensional assembly mode of the porphyrin units represents a supramolecular isomer of the unique three-dimensional coordination frameworks of the same porphyrin building block observed earlier. The significance of this study lies in the discovery of an additional supramolecular isomer of the rarely observed structures of metalloporphyrins self-assembled directly into extended coordination polymers without the use of external ligand or metal ion auxiliaries.

Download Full-text