Search results for "ferromagnetism"
showing 10 items of 940 documents
Double resonance response in nonlinear magnetic vortex dynamics
2013
We present experimental evidences for the dynamical bifurcation behavior of ac-driven magnetic vortex core gyration in a ferromagnetic disk. The dynamical bifurcation, i.e., appearance and disappearance of two stable dynamical states in the vortex gyration, occurring as the amplitude of the driving Oersted field increases to ${B}_{Oe}g{B}_{Oe}^{cr}$, manifests itself in a double resonance response in the dependence of homodyne the dc-voltage signal on the frequency $\ensuremath{\omega}$ of the applied microwave current. We find that the frequency range $\ensuremath{\delta}\ensuremath{\omega}$ between the two resonance features strongly increases with the excitation power. Our analysis based…
Switching by Domain-Wall Automotion in Asymmetric Ferromagnetic Rings
2017
A ring-shaped magnetic logic device offers two vortex states (clockwise and counterclockwise) to encode bits, with relative stability against external magnetic fields. The dynamics of magnetization switching in such structures, though, still need unraveling. The authors present direct experimental visualization of reproducible, robust switching in magnetic rings via domain-wall automotion, which does not require an applied field. Simulations reveal that annihilation of domain walls through automotion always occurs, with the detailed topology of the walls only influencing the dynamics locally, in line with the experimental results.
Localized domain wall nucleation dynamics in asymmetric ferromagnetic rings revealed by direct time-resolved magnetic imaging
2016
We report time-resolved observations of field-induced domain wall nucleation in asymmetric ferromagnetic rings using single direction field pulses and rotating fields. We show that the asymmetric geometry of a ring allows for controlling the position of nucleation events, when a domain wall is nucleated by a rotating magnetic field. Direct observation by scanning transmission x-ray microscopy (STXM) reveals that the nucleation of domain walls occurs through the creation of transient ripplelike structures. This magnetization state is found to exhibit a surprisingly high reproducibility even at room temperature and we determine the combinations of field strengths and field directions that all…
Very Long Term Stabilization of a 2D Magnet down to the Monolayer for Device Integration
2020
2D materials have recently demonstrated a strong potential for spintronic applications. This has been further reinforced by the discovery of ferromagnetic 2D layers. Nevertheless, the fragility of ...
Two bimetallic layered materials with “Cu4Fe3” defective cubane units: syntheses, structures and magnetic properties of {[CuII(tn)]2[FeII(CN)6]}3·[Na…
2005
Abstract Reactions of the [Fe III (CN) 6 ] 3− anion with the [Cu II (tn)] 2+ ion (tn = 1,3-diaminopropane) afford the compounds {[Cu II (tn)] 2 [Fe II (CN) 6 ]}3·[Na 3 Fe III (CN) 6 ]·12H 2 O (1) and {[Cu n (tn)] 2 [Fe II (CN) 6 ]}·KCl·5H 2 O (2). Despite the differences concerning their asymmetric units, both structures present strong similar features: in both structures, the Cu(II) ion presents a square-base pyramidal CuN 5 environment and each [Fe II (CN) 6 ] 4− anion is linked to six Cu(II) ions through its six N atoms leading to infinite [Cu II (tn)] 2 [Fe II (CN) 6 ] layers which can be viewed as 2-D layered arrangement generated by the defective cubane units Cu 4 Fe 3 involving Fe-CN…
Planar Benzo[1,2-b:4,5-b′]dithiophene Derivatives Decorated with Nitronyl and Imino Nitroxides
2018
Four weakly antiferromagnetic interacting biradicals of benzo[1,2- b:4,5- b']dithiophene (BDT) and BDT extended with two thiophenes (BDTTh2) linked with nitronyl and imino nitroxides (NN and IN) as BDT-NN, BDT-IN, BDTTh2-NN, and BDTTh2-IN were designed, synthesized, and characterized. Short intermolecular π-π distances were found (3.42 A) for BDT-NN, whereas larger ones were found for BDT-IN (3.54 A) and BDTTh2-NN (3.67 A), respectively. Intramolecular magnetic interaction ( Jintra,exp/ kB) of BDT-NN (-26 K) is much larger than for BDT-IN (-5.3 K), while it is reduced for the dithiophene-extended molecule BDTTh2-NN (-2.3 K). Intermolecular interactions ( zJinter,exp/ kB) of BDT-NN (-6.5 K) …
A hybrid magnet with coexistence of ferromagnetism and photoinduced Fe(iii) spin-crossover
2011
International audience; The insertion of a [Fe(sal2-trien)]+ complex cation into a 2D oxalate network results in a hybrid magnet with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compound [FeIII(sal2-trien)][MnIICrIII(ox)3]*(CH2Cl2) (1). A complete photomagnetic characterization together with a detailed structural analysis of the low-spin (LS) and high-spin (HS) structures of 1 is presented in order to understand such unusual behavior. This very rare and unexpected property in a FeIII spin-crossover complex, has been attributed to the strong distortion exhibited by the metastable HS state. Furthermore, 1 has shown that, in contrast to what has been pre…
Oxotris(oxalate)niobate(V): An oxalate delivery agent in the design of building blocks
2018
This work concerns the oxalate delivery process that occurs when using (NH4)3[NbO(C2O4)3]·6H2O as a suitable oxalate source in the synthesis of two compounds, [Cu(dmphen)(C2O4)(H2O)] (1) and [{Cu(dmphen)(CH3OH)}2(μ-C2O4)](ClO4)2 (2) (dmphen = 2,9-dimethyl-1,10-phenanthroline). {[Fe{HB(pz)3}(CN)2(μ-CN)]2[{Cu(dmphen)}2(μ-C2O4)]}∙xCH3OH (3) (2.0 ≤ x ≤ 2.4) was obtained by reacting 2 and PPh4[Fe{HB(pz)3}(CN)3]∙H2O [ = tetraphenylphosphonium and = tris(pyrazolyl)borate]. Crystal structures of 1–3 have been determined by single-crystal X-ray diffraction experiments: 1 is a mononuclear trigonal bipyramidal copper(II) species, 2 is a centrosymmetric oxalato-bridged dicopper(II) complex, and 3 consi…
Synthesis, crystal structures and magnetic properties of picolinate-bridged copper(II) chains
2018
The paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) coordination polymers, Cu2(L1)4 (1) and Cu3(L2)6 (2), based on rigid ethynylene-bridged ditopic ligands containing one picolinate subunit (L1 = 5-(pyridin-3-ylethynyl)picolinate anion; L2 = 5-((4-(methoxycarbonyl)phenyl)ethynyl)picolinate anion). Both 1 and 2 have a chain structure. In 1, the repeating unit in the chain is a doubly bridged picolinate dicopper(II) complex, whereas 2 is built upon trimeric units where the Cu2+ ions are also connected by double picolinate bridges. Both compounds exhibit antiferromagnetic interactions in the solid state. The magnetic properties of 1 and 2 were analyze…
Synthesis, Crystal Structure and Magnetic Properties of Heteropolynuclear Re IV M II Complexes Based on the Robust [ReCl 5 (pyzCOO)] 2– Unit (pyzCOO …
2016
The syntheses, crystal structures and magnetic properties of four rhenium(IV) compounds of formulae NBu4[ReCl5(pyzCOOH)]·H2O (1), [ReCl5(µ-pyzCOO)M(dmphen)2]·2CH3CN [M = Ni (2) and Co (3)] and {[ReCl5(µ3-pyzCOO)]2Mn2(dmphen)3}n (4) (NBu4 = tetra-n-butylammonium cation, pyzCOOH = 2-pyrazinecarboxylic acid, dmphen = 2,9-dimethyl-1,10-phenanthroline) are reported herein. Compound 1 was obtained by the reaction of NBu4[ReCl5(dmf)] (dmf = dimethylformamide) with pyzCOOH in acetone, whereas the other complexes were obtained by the reaction of 1 with M(ClO4)2·6H2O [M = Ni (2), Co (3), Mn (4)] and dmphen in acetonitrile. Complex 1 is a mononuclear compound, 2 and 3 are neutral heterodinuclear compl…