DMI across AFM-FM Interface

Dzyaloshinskii-Moriya Interaction across an Antiferromagnet-Ferromagnet Interface.

Xin Ma, Guoqiang Yu, Seyed A. Razavi, Stephen S. Sasaki, Xiang Li, Kai Hao, Sarah H. Tolbert, Kang L. Wang, and Xiaoqin Li

Phys. Rev. Lett. 119, 027202 (2017)

(a) Schematics of BLS experiment and possible atomic arrangement at the interface. (b) BLS spectra for DE spin waves recorded at a fixed incident angle with $k=16.7\mathrm{rad}/\mu m$ under oppositely oriented external magnetic fields $H$. The solid lines represent fittings with Lorentzian functions.

DW dynamics in synthetic antiferromagnets

Novel domain wall dynamics in synthetic antiferromagnets.
See-Hun Yang and Stuart Parkin J. Phys.: Condens. Matter 29, 303001 (2017)

Illustration of the ECT driven DW motion in SF (a) and SAF (b) wires in the presence of spin Hall torque and DMI field.

Magnetic skyrmions: Review of recent advances

Magnetic skyrmions: advances in physics and potential applications.
Albert Fert, Nicolas Reyren,Vincent Cros
Nature Reviews Materials 2, 17031 (2017)

Skyrmions in Noncentrosymmetric Magnets: Review

Noncentrosymmetric Magnets Hosting Magnetic Skyrmions.

Naoya Kanazawa, Shinichiro Seki, and Yoshinori Tokura

Advanced Materials 29, 1603227 (2017)

Equilibrium magnetization and magnetization relaxation of multicore magnetic nanoparticles

Equilibrium magnetization and magnetization relaxation of multicore magnetic nanoparticles.
Patrick Ilg
Phys. Rev. B 95, 214427 (2017)

Left: Visualization of a dense random cluster containing $N=100$ nanoparticles prepared as described in Sec. 3a. Right: Visualization of a cluster containing $N=100$ nanoparticles prepared by DLCA with $Q_{\mathrm{dd}}=2$ and $\varepsilon =4$ as described in Sec. 3b.

Surface design of magnetic nanoparticles for stimuli-responsive cancer imaging and therapy

Surface design of magnetic nanoparticles for stimuli-responsive cancer imaging and therapy
Taegyu Kang, Fangyuan Li, Seungmin Baik, Wei Shao, Daishun Ling, Taeghwan Hyeon
Biomaterials 136, 98 (2017)

Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen - ACS Nano (ACS Publications)

Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen.

Mythreyi Unni,Amanda M. Uhl, Shehaab Savliwala, Benjamin H. Savitzky, Rohan Dhavalikar, Nicolas Garraud, David P Arnold, Lena F. Kourkoutis, Jennifer S. Andrew, and Carlos Rinaldi

ACS Nano 11, 2284 (2017)

Decades of research focused on size and shape control of iron oxide nanoparticles have led to methods of synthesis that afford excellent control over physical size and shape but comparatively poor control over magnetic properties. Popular synthesis methods based on thermal decomposition of organometallic precursors in the absence of oxygen have yielded particles with mixed iron oxide phases, crystal defects, and poorer than expected magnetic properties, including the existence of a thick “magnetically dead layer” experimentally evidenced by a magnetic diameter significantly smaller than the physical diameter. Here, we show how single-crystalline iron oxide nanoparticles with few defects and similar physical and magetic diameter distributions can be obtained by introducing molecular oxygen as one of the reactive species in the thermal decomposition synthesis. This is achieved without the need for any postsynthesis oxidation or thermal annealing. These results address a significant challenge in the synthesis of nanoparticles with predictable magnetic properties and could lead to advances in applications of magnetic nanoparticles.

Standardizing Size- and Shape-Controlled Synthesis of Monodisperse Magnetite (Fe3O4) Nanocrystals by Identifying and Exploiting Effects of Organic Impurities

Standardizing Size- and Shape-Controlled Synthesis of Monodisperse Magnetite Nanocrystals by Identifying and Exploiting Effects of Organic Impurities.

Liang Qiao, Zheng Fu, Ji Li, John Ghosen, Ming Zeng, John Stebbins, Paras N. Prasad, and Mark T. Swihart

ACS Nano 11, 6370 (2017)

Size-Dependent Heating of Magnetic Iron Oxide NP

Size-Dependent Heating of Magnetic Iron Oxide Nanoparticles.
Sheng Tong, Christopher A. Quinto, Linlin Zhang, Priya Mohindra, and Gang Bao

ACS Nano 11, 6808 (2017)

Single crystalline cylindrical nanowires – toward dense 3D arrays of magnetic vortices : Scientific Reports

Single crystalline cylindrical nanowires – toward dense 3D arrays of magnetic vortices.
Yurii P. Ivanov, Andrey Chuvilin, Laura G. Vivas, Jurgen Kosel, Oksana Chubykalo-Fesenko & Manuel Vázquez
Scientific Reports 6, Article number: 23844 (2016)
Scientific Reports 6, 23844 (2016)

(a) Calculated dependence of the total energy of the vortex and non-vortex state on the length of NWs. (b) The nucleation field of the vortex and the switching field for the vortex core as a function of NW length after saturation in 1 T parallel to the NW axis. (c) Simulated magnetization of single-crystal hcp Co NW with a 75-nm diameter, depending on the length of the NW.

DW annhilation in wires

Annihilation of domain walls in a ferromagnetic wire.

Anirban Ghosh, Kevin S. Huang, and Oleg Tchernyshyov

Phys. Rev. B 95, 180408(R) (2017)

Several configurations of a pair of domain walls with shown values of separation $\zeta$ and twist $\phi$. The red and blue colors denote positive and negative magnetization component $m_z$ along the axis of the cylinder. The wire frames depict the local plane tangential to the magnetization field. Spheres on the right show the path of the magnetization field $m\left(z\right)$ as $z$ goes from $-\infty$ to $+\infty$, beginning from and ending at the north pole (red). The south pole (blue) can only be reached if the separation of the domain walls $\zeta =\infty$.

Effect of volume distribution broadenig in properties of NPs

Magnetic properties of nanoparticle compacts with controlled broadening of the particle size distribution.

M. S. Andersson, R. Mathieu, P. S. Normile, S. S. Lee, G. Singh, P. Nordblad, and J. A. De Toro

Phys. Rev. B 95, 184431 (2017)

(a) Low-field (800 A/m) ZFC/FC M/H vs $T$ curves for MIX0 and a diluted sample from the same nanoparticle batch (reference MIX0). M/H values are normalized to the maximum of their ZFC M/H curves. (b) In-phase (${\chi }^{\prime }$) and (c) out-of-phase (${\chi }^{\text{'}\text{'}}$) components of the ac susceptibility as a function of the temperature ($f=10$ Hz) for selected compacts as in the legend in (c). Inset in (b): Temperature of the maximum of the in-phase susceptibility ($T_{\max }$) as a function of the concentration of 11.5-nm particles.

DM interaction in transition-metal chains

Role of Dzyaloshinskii-Moriya interaction for magnetism in transition-metal chains at Pt step edges.
B. Schweflinghaus, B. Zimmermann, M. Heide, G. Bihlmayer, and S. Blügel
Phys. Rev. B 94, 024403 (2016)

Role of the antiferromagnetic bulk spins in exchange bias

Role of the antiferromagnetic bulk spins in exchange bias.
Ivan K. Schuller, Rafael Morales, Xavier Batlle, Ulrich Nowak, Gernot Güntherodt
JMMM 416, 2 (2016)

Skyrmion excitations in a magnonic crystal

Collective dynamical skyrmion excitations in a magnonic crystal.

M. Mruczkiewicz, P. Gruszecki, M. Zelent, and M. Krawczyk
Phys. Rev. B 93, 174429 (2016)

Spatial maps of the x, y, and z components of the dynamic magnetization vector δm of (a) the 0.98 GHz clockwise gyrotropic mode, and (b) the 13.24 GHz breathing mode, obtained from FDTD simulations in a 30-nm nanodot under magnetic field Bz=0.1 T. Left and right columns show the absolute value and phase, respectively, of each δm component.

Magnetic properties of large Co clusters

Structural and magnetic properties of large cobalt clusters.
Jaime Souto-Casares, Masahiro Sakurai, and James R. Chelikowsky
Phys. Rev. B 93, 174418 (2016)

Local magnetic moment per atom with respect to the coordination number. Error bars represent the minimum and maximum value. Each set of points has been fitted to a line. A miniature of the specific cluster is shown, with the color map representing the individual local magnetic moment growing in the upper direction.

Rewritable artificial magnetic charge ice

Rewritable artificial magnetic charge ice.

Yong-Lei Wang, Zhi-Li Xiao,Alexey Snezhko, Jing Xu,Leonidas E. Ocola, Ralu Divan,John E. Pearson, George W. Crabtree, Wai-Kwong Kwok

Science 352, 962 (2016)

Rewritable magnetic charge ices. (A) Sketch of the experimental setup: an MFM equipped with a 2D vector magnet. The 2D solenoid magnet provides magnetic fields in any desired orientation in the sample plane. The vertically magnetized MFM probe generates a stray magnetic field (green arrows) with in-plane components at the tip. (B) Magnetization loop of a single magnetic island, with an illustration of the write, erase, and read functions. M_x, magnetization along the island. (C to G) Magnetic force microscopy images of the patterned magnetic charge ice at the same area of the sample. (C) The initial state is a type I₁ state. (D) A square area of a type III₃ state was written in the center of (C). (E) A smaller square region of type III₃ order was erased back to a type I₁ state from (D). (F) A round region of type II₂ order was written onto the freshly erased area from (E). (G) “ICE” letters of type III₄ states were scribed on a type I background state.

Multidomain Skyrmion Lattice

Multidomain Skyrmion Lattice State in Cu2OSeO3.

S. L. Zhang, A. Bauer, D. M. Burn, P. Milde, E. Neuber, L. M. Eng, H. Berger, C. Pfleiderer, G. van der Laan, and T. Hesjedal

 Nano Letters (ACS Publications)

Bubble and skyrmion crystals

Bubble and skyrmion crystals in frustrated magnets with easy-axis anisotropy.
Satoru Hayami, Shi-Zeng Lin, and Cristian D. BatistaPhys. Rev. B 93, 184413 (2016)

Schematic views of (a) a noncoplanar skyrmion texture and (b) a collinear bubble. Triangular crystals of these structures are induced by magnetic field and easy-axis anisotropy in high-symmetry frustrated magnets.

Interplay between anisotropy and EB in films

Interplay between magnetocrystalline anisotropy and exchange bias in epitaxial CoO/Co films.
Hao-Liang Liu, Steven Brems, Yu-Jia Zeng, Kristiaan Temst, André Vantomme and Chris Van Haesendonck
Journal of Physics: Condensed Matter 28, 196002 (2016)

Surface vacancy mediated pinning in maghemite NP

Surface vacancy mediated pinning of the magnetization in γ−Fe2O3 nanoparticles: A micromagnetic simulation study

Bassel Alkadour, J. I. Mercer, J. P. Whitehead, J. van Lierop, and B. W. Southern

Phys. Rev. B 93, 140411(R) (2016)

The energy landscape for a nanoparticle selected at random from the K10 enemble. Each point on the surface of the sphere represents the energy associated with the alignment of the magnetic moment. The energy is calculated using a mean field approximation based on the distribution of surface vacancies and the average angular distribution of the energy per spins at T=0 shown in Fig. 4. The energy scale associated with the color map shown on the right is given in K.

Vortex induced by impurity

Magnetic Vortex Induced by Nonmagnetic Impurity in Frustrated Magnets
Shi-Zeng Lin, Satoru Hayami, and Cristian D. Batista
Phys. Rev. Lett. 116, 187202 (2016)

Vortex solutions for $H_{\mathrm{sat}}<H<H_{\mathrm{sat}}^I$obtained from numerical simulations of $H$ in the classical limit ($S\to \infty$). (a) Vortex bound to a single-site nonmagnetic impurity for different field values. The vortex helicity is arbitrary due to the U(1) symmetry of $H$. (b) Giant vortex solution ($l=\pm 2$) obtained after removing the spins from the six sites indicated with black dots, for $J_3=-0.2777J_1$ and $Q=2\pi /12$. The saturation field is $H_{\mathrm{sat}}=0.02235\left|J_1\right|$ and $H_{\mathrm{sat}}^I=0.04725\left|J_1\right|$.