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| Topography of mz during the skyrmion polarity switching process. The insets on the lower right show mz in the disk plane. The insets on the upper right display the cutlines along the diameter through the disk center. (i) Variation of the Rs with simulation time. |
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| Illustration of two magnetic modes in an antiferromagnetic nanoparticle with a vertical easy axis. The A (B) sublattice points in the +z(−z) direction and describes a blue (red) trajectory: (top) a uniform in-plane magnetic mode; the ωα mode; (bottom) the “rotor mode.” |
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| Imprinting non-collinear magnetic spin textures into out-of-plane magnetised films (Co/Pd multilayers) via interlayer coupling to a vortex state (Permalloy, Py) (a). Calculations are carried out for a Co/Pd anisotropy of Ku = 200 kJ/m3. Depending on the interlayer exchange coupling strength and the magnetic field treatment (remanence or relaxed state), configurations of distinct topology can be imprinted in the out-of-plane magnetised layer as revealed by micromagnetic simulations. Figures (b)–(e) show the magnetic configuration of four different states in Co/Pd films with decreasing strength of interlayer coupling Ji (left to right) after applying an out-of-plane magnetic field. Colours correspond to the normalised out-of-plane magnetisation component: (b) Remanent and relaxed vortex state; (c)–(d) remanent donut state type II and type I (number of domain walls), respectively; and (e) relaxed magnetic spiral. The skyrmion number S of each state is assessed based on the sketched magnetisation configuration in the cross-section. (f) Line profiles through the center of the Co/Pd film for the normalised out-of-plane magnetisation (mz = Mz/Ms) in remanent state Co/Pd spins illustrate the possibility to tailor the opening angle of the donut state by adjusting Ji. The magnetic spiral also appears after opening the circular domain wall of the donut state by applying a small in-plane magnetic field. |
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| Cobalt atoms exposed to hydrogen gas have higher spins, an effect that could be used to build magnetic nanostructures and lattices. |
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| Semilog plots of q̃2(t0,t) and q2 vs time t (in MC sweeps) for DIS systems with concentration x=0.35 running at the lowest temperature Tn for the values of L indicated in the figure. T=0.075(T=0.05) for L=10(L=8). |
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| AMR spectra measured on a disk shaped sample for (a) up (p=+1) and (b) down (p=−1) polarization of the vortex core for an excitation current of 1.2 mA. The sample design is shown in the inset of (a). By applying a rotating current (counterclockwise or clockwise) the VC polarity can be switched selectively to up or down. A sign change of the AMR voltage signal can be observed for the two polarities. Note that a significant shift of the resonance frequency to higher frequencies is observed at larger bias fields. Also note that the fine structure observed in the spectra does not depend on the VC polarity. |
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| Reduced ordered plus induced moment μ¯i≡μi/μsat versus reduced staggered magnetic field h†≡gμBH†/kBTN at the indicated reduced temperatures t≡T/TN for (a) spin S=1/2 and (b) spin S=7/2. |
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| Sketch of a quantum communication channel and properties of spins entangled through antiferromagnetic interactions |
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| Hysteresis loops for FeF2(70 nm)/NiFe (30 and 100 nm) bilayers at (a) T=10 and (b) T=70 K. Symbol: Experimental data. Blue solid line in (a): Simulation. |
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| (a) Size dependence of experimentally measured (black solid (T = 5 K) and dashed (300 K) lines) and calculated saturation magnetization MS of CoO octahedra. A magnetic moment μ of (4.8 ± 0.4)μB per Co2+ ion and a shell thickness of 3 nm Co3O4 is assumed. MS arises only from the Co cations at the surfaces or interfaces of the octahedral nanocrystals, as indicated in the schematic in (b). The blue lines are calculated values assuming only effectively one layer of Co2+ cations at the Co3O4 surface, while the red lines correspond to a double layer of Co cations at the interface. |
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Cobalt
oxide octahedra were synthesized by thermal decomposition. Each
octahedron-shaped nanoparticle consists of an antiferromagnetic CoO core
enclosed by eight {111} facets interfaced to a thin (∼4 nm) surface
layer of strained Co3O4. The nearly perfectly
octahedral shaped particles with 20, 40, and 85 nm edge length show a
weak room-temperature ferromagnetism that can be attributed to
ferromagnetic correlations appearing due to strained lattice
configurations at the CoO/Co3O4 interface.
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| Increased coercive and tunable exchange bias field values were registered in hybrid CoO@Fe3O4 core–shell octahedron-shaped nanoparticles of different average size. In this strained morphology, the metal cation chemical potentials at the interface between the antiferromagnetic and ferrimagnetic oxides become a very dynamic variable. This causes the effective magnetic anisotropy to increase and the type of interface to change after growing the magnetite shell epitaxially onto the cobalt oxide {111} surface facets and, consequently, to tune the exchange bias effect. |
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| Spin dynamics of the skyrmion excited by an AC magnetic field
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| Examples of magnetic and spintronic properties that can be controlled by an electric field. DOS denotes density of states. |
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| Spin textures of cubic chiral helimagnets and their collective excitations. |
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| TRM for FexNi1−xF2 samples measured in H=0 after field cooling in HFC=100 Oe. Data for x=0 and 0.10 were measured with HFC perpendicular to the c axis; all others measured with HFC parallel to the c axis. Right: Magnetic and crystalline structures of the parent compounds NiF2 (x=0) and FeF2 (x=1). Yellow, blue, and red dots are F−, Ni2+, and Fe2+ ions, respectively. |
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| (a) Illustration of the head-to-head DW in the nanowire using red-blue opaque arrows. The translucent purple arrows represent a spin wave excitation. The DMI exerts a torque to change the DW tilt angle when spin waves pass through the DW. (b) DW profile using Eq. (5) with parameters A=8.78×10-12 J/m, K=1×105 J/m3, D=1.58×10-3 J/m2, K⊥=0 and Φ=0. The red dashed line shows the simulation data for mz with K⊥2=6×105 J/m3: the easy-plane anisotropy favors a reduced mz. (c) The dispersion relations inside and outside the DW |
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| Spin textures of cubic chiral helimagnets and their collective excitations. |
