Quantum deflagration in molecular magnets

Quantum deflagration and supersonic fronts of tunneling in molecular magnets.
D. A. Garanin and Saaber Shoyeb
ArXiv 1112.5171 (2011)

Spatial profiles of the deflagration front in a small transverse field, B? = 0:05 T at the peak of the front speed at Bz = 2:852 T. There is a resonance spin tunneling at the face of the front and burning in its central and rear parts.

Magnetotactic bacteria

A Cultured Greigite-Producing Magnetotactic Bacterium in a Novel Group of Sulfate-Reducing Bacteria.
Christopher T. Lefèvre, Nicolas Menguy, Fernanda Abreu, Ulysses Lins, Mihály Pósfai, Tanya Prozorov, David Pignol, Richard B. Frankel, Dennis A. Bazylinski
Science 334, 1720 (2011)

"Trimerons" in Verwey structure of magnetite

Charge order and three-site distortions in the Verwey structure of magnetite.
Mark S. Senn, Jon P. Wright & J. Paul Attfield
Nature 481, 173 (2011)

Charge, orbital and trimeron order in the low-temperature magnetite structure.

Exchanged biased molecular clusters

A Supramolecular Aggregate of Four Exchange-Biased Single-Molecule Magnets.
Tu N. Nguyen, Wolfgang Wernsdorfer,  Khalil A. Abboud, and George Christou
JACS 133, 20688 (2011)

Hysteresis loops in plots of magnetization vs dc field for a single crystal of 3·xCH2Cl2 (top) at the indicated temperatures at 0.28 T/s and (bottom) at the indicated field scan rates at 0.04 K. M is normalized to its saturation value, MS.

First-principles calculation of the nonadiabatic spin transfer torque in Ni and Fe.
Keith Gilmore, Ion Garate, Allan H. MacDonald, and M. D. Stiles
Phys. Rev. B 84, 224412 (2011)

Spin-transfer torque parameter versus resistivity for several ratios (r = 0.5, 1.0, 2.0) of spin-dependent scattering rates for Ni. The top panel gives β, the middle panel β/α, and the bottom panel βσP/(ασ). The dashed vertical lines indicate
the approximate room-temperature resistivity.

Fe films with spins spiral states from ab initio

Thickness-dependent magnetic structure of ultrathin Fe/Ir(001) films: From spin-spiral states toward ferromagnetic order.
A. Deák and L. Szunyogh, B. Ujfalussy
Phys. Rev. B 84, 224413 (2011)

Ground-state spin configurations of the Fe monolayer with experimental layer relaxation (a) without and (b) with
biquadratic couplings.

Coulomb field of spin ice monopoles

A field trip through spin ice.
G. Sala, C. Castelnovo, R. Moessner, S. L. Sondhi, K. Kitagawa, M. Takigawa, R. Higashinaka, and Y. Maeno
ArXiv 1112.3363 (2011)

Monopolar field inside spin ice – Illustration of the magnetic
field of a monopole at the centres of the super-tetrahedra of the
pyrochlore lattice, visualised by unit vectors in the local field direction
(red-blue arrows).

Inverse Faraday effect and ulytafast magnetization

Theory of the inverse Faraday effect in view of ultrafast magnetization experiments.
Daria Popova, Andreas Bringer, and Stefan Blügel
Phys. Rev. B 84, 214421 (2011)

The three-level system investigated. The laser pulse causes transitions from the initial state |i to the
intermediate |j  and then to the final one |f , with a magnetic state different from the one of the initial state.

Order by disorder in a triangular lattice

Order by disorder and phase transitions in a highly frustrated spin model on the triangular lattice.
A. Honecker, D. C. Cabra, H.-U. Everts, P. Pujol, and F. Stauffer
Phys. Rev. B 84, 224410 (2011)

Snapshot of a configuration during a simulation for J < 0 at T = 10−3|J | on a 12 × 12 lattice. Periodic
boundary conditions are imposed at the edges.

Dipolar order in 2D spin systems

Dipolar ordering of random two-dimensional spin ensemble.
Andrey V. Panov
ArXiv 1112.2776 (2011)

Phase diagrams for dipoles with random orientation of axes. The areas under the curves correspond to the ordered states, Tc is Curie temperature of nanoparticles material, Td is the critical temperature of dipolar ordering.

Dipolar ordering in NPs by holography

Dipolar ferromagnetic phase transition in Fe3O4 nanoparticle arrays observed by Lorentz microscopy and electron holography.
Kazuo Yamamoto, Charles R. Hogg, Saeki Yamamuro, Tsukasa Hirayama, and Sara A. Majetich
Appl. Phys. Lett. 98, 072509 (2011)

Temperature dependence of magnetic induction maps determined from the reconstructed phase images.

IOPscience::.. Journal of Physics: Condensed Matter, Volume 24, Number 2, 18 January 2012

Special issueon DW dynamics in nanostructures.
Edited by C H Marrows and G Meier.
Journal of Physics: Condensed Matter, Volume 24, Number 2, 18 January 2012

Among them you may find:
1. Temperature-dependent dynamics of stochastic domain-wall depinning in nanowires  
Clemens Wuth, Peter Lendecke and Guido Meier
Page 024207

2. Enhanced functionality in magnonics by domain walls and inhomogeneous spin configurations  
G Duerr, R Huber and D Grundler
Page 024218

3. Domain wall motion in perpendicular anisotropy nanowires with edge roughness  
Maximilian Albert, Matteo Franchin, Thomas Fischbacher, Guido Meier and Hans Fangohr  
Page 024219

4. Determination of the spin torque non-adiabaticity in perpendicularly magnetized nanowires  J Heinen, D Hinzke, O Boulle, G Malinowski, H J M Swagten, B Koopmans, C Ulysse, G Faini, B Ocker, J Wrona and M Kläui
Page 024220

Electric switching of magnets

Electric toggling of magnets.
Evgeny Y. Tsymbal
Nature Mater. 11, 3205 (2012)

Electric-field-induced toggle switching of magnetization. a, Schematic of the experiment performed by Wang and colleagues.

Fields inside spin ice

A field trip through spin ice.
G. Sala, C. Castelnovo, R. Moessner, S. L. Sondhi, K. Kitagawa, M. Takigawa, R. Higashinaka, and Y. Maeno
ArXiv, 1112.3363 (2011)

Monopolar field inside spin ice – Illustration of the magnetic field of a monopole at the centres of the super-tetrahedra of the pyrochlore lattice, visualised by unit vectors in the local field direction (red-blue arrows).

Magnetoplasmonics with nano FMs

Designer Magnetoplasmonics with Nickel Nanoferromagnets.
Valentina Bonanni, Stefano Bonetti, Tavakol Pakizeh, Zhaleh Pirzadeh, Jianing Chen, Josep Nogués, Paolo Vavassori, O Rainer Hillenbrand, O Johan Åkerman, and Alexandre Dmitriev
Nano. Lett. 11, 533 (2011)

We introduce a new perspective on magnetoplasmonics in nickel nanoferromagnets by exploiting the phase tunability of the optical polarizability due to localized surface plasmons and simultaneous magneto-optical activity. We demonstrate how the concerted action of nanoplasmonics and magnetization can manipulate the sign of rotation of the reflected light’s polarization (i.e., to produce Kerr rotation reversal) in ferromagnetic nanomaterials and, further, how this effect can be dynamically controlled and employed to devise conceptually new schemes for biochemosensing.

Interfacial coupling by FMR

Interfacial coupling across a modifi ed interface studied with ferromagnetic resonance.
R. Magaraggia, S. McIntyre, and K. Kennewell, R. L. Stamps, M. Ali, D. Greig, B. J. Hickey, and C. H. Marrows.
ArXiv 1112.2045 (2011)

(a) FMR resonance field for a 60.5 nm NiFe film with a resonance frequency of 3 GHz as a function
of exchange coupling Jint to a 6 nm thick IrMn antiferromagnet. (b) The FEX resonance field with a resonance frequency.

Bloch points in nanospheres

Bloch Point Structure in a Magnetic Nanosphere.
Oleksandr V. Pylypovskyi, Denis D. Sheka, and Yuri Gaididei
ArXiv 1112.2413 (2011)

Dynamics of total spin along z axis of sample with a Bloch point initially shifted from center of the sample.

Hardening of the NP-protein corona in oxide NPs

Hardening of the Nanoparticle–Protein Corona in Metal (Au, Ag) and Oxide (Fe3O4, CoO, and CeO2) Nanoparticles.
Eudald Casals, Tobias Pfaller, Albert Duschl, Gertie J. Oostingh, Víctor F. Puntes
Small 7, 3479 (2011)

Simulating SWs dispersion in nanostructures

Numerical calculation of spin wave dispersions in magnetic nanostructures.
Dheeraj Kumar, Oleksandr Dmytriiev, Sabareesan Ponraj and Anjan Barman
J. Phys. D 45, 015001 (2012)

Static magnetic configurations (in-plane) of the central portion of the simulated sample with H applied (a) along the length and (b) across the width of the permalloy ample with 3 rows of 1D array of square anti-dots imprinted in it. (c and d) Corresponding simulated dispersion of symmetric modes.

Perpendicular spin torque in MTJs

Measurement of perpendicular spin torque at high bias via the pulsed switching phase diagram
Seung-Young Park, Younghun Jo, and Kyung-Jin Lee
Phys. Rev. B 84, 214417 (2011)

Experimental measurements of (a) dc switching phase diagram and (b) pulsed switching phase diagrams. In
(b), the switching boundaries of dc switching phase diagram is added for comparison (red dashed lines).

AF in triangular lattice

Phase diagram of the classical Heisenberg antiferromagnet on a triangular lattice in an applied magnetic field.
Luis Seabra, Tsutomu Momoi, Philippe Sindzingre, and Nic Shannon
Phys. Rev. B 84, 214418 (2011)

Magnetic phase diagram of the AFM Heisenberg model on a triangular lattice, obtained from MC simulation. Continuous phase transitions are drawn with a dashed line, while Berezinskii-Kosterlitz-Thouless phase transitions are drawn
with a dotted line.

Atom manipulation with DWs

Manipulating ultracold atoms with a recon gurable nanomagnetic system of domain walls.
A. D. West, K. J. Weatherill, T. J. Hayward, P. W. Fry, T. Schrefl, M. R. J. Gibbs, C. S. Adams, D. A. Allwood, and I. G. Hughes
ArXiv 1112.0485 (2011)

A schematic representation of the experiment. The array of undulating nanowires is shown. The wires are 125 nm wide and 30 nm thick and have a periodicity of 1 nm. The wire shading represents the magnetic polarity; the wires are shown in the `on' state, hosting DWs at each apex. Also indicated are magnetic fi eld lines emanating from and entering the DWs. Above the wires is shown the magnetic potentialisosurface corresponding to a value of  B = 1:57 mT.

FeO/Au NPs for bimodal imaging

Facile Synthesis of Monodisperse Superparamagnetic Fe3O4 Core@hybrid@Au Shell Nanocomposite for Bimodal Imaging and Photothermal Therapy.
Wenjie Dong , Yongsheng Li , Dechao Niu , Zhi Ma , Jinlou Gu , Yi Chen , Wenru Zhao , Xiaohang Liu , Changsheng Liu , and Jianlin Shi
Adv. Mater. 23, 5392 (2011)

The as-prepared nanocomposite is demonstrated to have a great potential for magnetic resonance imaging (MRI)-guided, focused photothermal tumor therapy under near-IR laser radiation.

Vortex reversal by spin waves

200 ps Vortex Core Reversal by Azimuthal Spin Waves.
Matthias Kammerer, Hermann Stoll, Matthias Noske, Markus Sproll, Markus Weigand, Georg Woltersdorf, and Gisela Schuetz
ArXiv 1112.1903 (2011)

Time-resolved imaging of spin wave mediated vortex core reversal. B: Amplitudes in x and y direction of the CW (left) and CCW (right) rotating bursts of one period at 4:5GHz. A and C: Snapshots in steps of 58:5 ps showing the
out-of-plane magnetization of the excited spin wave during unidirectional reversal of the vortex core polarization from down to up (A) and from up to down (B).

Spin ice dynamics in honeycomb network

Dynamics of artificial spin ice: continuous honeycomb network.
Yichen Shen, Olga Petrova, Paula Mellado, Stephen Daunheimer, John Cumings, Oleg Tchernyshyov
ArXiv 1112.1857 (2011)

Left: Simulated magnetization curve M(H) (red circles) is well approximated by the theoretical curve (15) (solid black line). Inset: semi-log plot of the number of avalanches as a function of their length. Right: Experimental magnetization curve M(H) (red circles) [24] and the best fit to Eq. (15) (solid black line).

Magnetization reversal in antidots

Geometry-dependent magnetization reversal mechanism in ordered Py antidot arrays.
K J Merazzo, D C Leitao, E Jiménez, J P Araujo, J Camarero, R P del Real, A Asenjo and M Vázquez
JPD 44, 505001 (2011)

FORC diagrams of films with thickness tPy = 18 nm: (a) continuous film, and arrays of antidots with diameter (b) dp = 35 nm,
(c) dp = 48 nm and (d) dp = 54 nm.

DW pinning suppression

Suppression of the intrinsic stochastic pinning of domain walls in magnetic nanostripes.
Manuel Muñoz, and José L. Prieto
Nature Comms. 2, 562 (2011)

Enhanced pinning in the precessional mode and the pinning probability for different types of magnetic domain wall.

Theragnostic Nanomedicine

Special issue on Theranostic Nanomedicine.
Accounts of Chemical Research: Volume 44, Issue 10 (2011)

Contains, among others, the following review articles:

1.Surface Engineering of Iron Oxide Nanoparticles for Targeted Cancer Therapy.
Forrest M. Kievit and Miqin Zhang p. 853

2. Theranostic Magnetic Nanoparticles.
Dongwon Yoo, Jae-Hyun Lee, Tae-Hyun Shin, and Jinwoo Cheon p. 863

 

3. Monodisperse Magnetic Nanoparticles for Theranostic Applications.
Don Ho, Xiaolian Sun, and Shouheng Sun p. 875

4. Surface-Engineered Magnetic Nanoparticle Platforms for Cancer Imaging and Therapy.
Jin Xie, Gang Liu, Henry S. Eden, Hua Ai, and Xiaoyuan Chen p. 883

5. Multifunctional Mesoporous Silica Nanocomposite Nanoparticles for Theranostic Applications.
Ji Eun Lee, Nohyun Lee, Taeho Kim, Jaeyun Kim, and Taeghwan Hyeon p. 893

Multiferroic BiFeO at room T

Multiferroic Phase Transition near Room Temperature in BiFeO3 Films.
I. C. Infante, J. Juraszek, S. Fusil, B. Dupé, P. Gemeiner, O. Diéguez, F. Pailloux, S. Jouen, E. Jacquet, G. Geneste, J. Pacaud, J. Íñiguez, L. Bellaiche, A. Barthélémy, B. Dkhil, and M. Bibes
Phys. Rev. Lett. 107, 237601 (2011)

Hyperfine field distributions of the T-like component at different temperatures (e) and temperature dependence of the average hyperfine fields (f ). Dashed lines are Brillouin functions for Fe3þ (S ¼ 5=2) fitted to the data; solid lines correspond to model Hamiltonian simulations.

MQT in a superconductor

Dissipative macroscopic quantum tunneling in type-I superconductors.
R. Zarzuela, E. M. Chudnovsky, and J. Tejada
Phys. Rev. B 84, 184525 (2011)

Interface between normal and superconducting regions in a type-I superconductor, pinned by a planar defect in the XY plane.

MOKEstudy of artificial spin ice

Magneto-optical Kerr effect studies of square artificial spin ice.
K. K. Kohli, Andrew L. Balk, Jie Li, Sheng Zhang, Ian Gilbert, Paul E. Lammert, Vincent H. Crespi,
Peter Schiffer, and Nitin Samarth
Phys. Rev. B 84, 180412(R) (2011)

(a) Variation of coercivity at θ = 0 as a function of lattice spacing for square arrays. Measurements on various samples (arrays 1–4) are compared with micromagnetic simulations (black squares), comparing simulations of the same island outlines but with different spacing.  (b) Experiment and simulation for square arrays as a function of angle for the largest lattice spacing of 880 nm.

Supra Nanocrystallinities

Supra- and nanocrystallinities: a new scientific adventure.
M P Pileni
J. Phys. CM 23, 503102 (2011)

Typical morphologies of nanoparticles that are either single-domain nanocrystals. Calculated absorption spectra of (f) Au, (g) Ag and (h) Cu nanoparticles with cuboctahedral (blue), truncated octahedral (pink), decahedral (red) and icosahedral (green) morphologies.

Ultrafast magnetization dynamics: a Review

Electron theory of fast and ultrafast dissipative magnetization dynamics.
M Fähnle and C Illg
J. Phys. CM 23, 493201 (2011)

(a) A sketch of the equilibrium Fermi surface S for time t-dt and time t. In a strict equilibrium situation the yellow
states are occupied only at time t-dt, the red are occupied only at time t, whereas the blue states are occupied at both times. Panel (b) shows a sketch of the equilibrium band structure.

Ground state formation in artificial spin ice

Disorder strength and field-driven ground state domain formation in artificial spin ice: experiment, simulation and theory.
Zoe Budrikis, J.P. Morgan, J. Akerman, A. Stein, R.L. Stamps, Paolo Politi, S. Langridge, and C.H. Marrows
ArXiv 1111.6491 (2011)

MFM images of final states of open (a-d) and closed (e-h) arrays after rotation at selected hold fields. The black outline in (g) indicates a GS domain.

Quantum effects in a magnetic vortex

Quantum depinning of the magnetic vortex core in micron-size permalloy disks.
Ricardo Zarzuela, Saül Vélez, Joan Manel Hernandez, Javier Tejada, and Valentyn Novosad
Phys. Rev. B 85, 180401(R) (2012)

Temperature dependence of the magnetic viscosity S(T ) at H = 0 and 300 Oe.

Reversal in individual and interacting NPs

Magnetization reversal in isolated and interacting single-domain nanoparticles.
H. Kesserwan, G. Manfredi, J.-Y. Bigot, and P.-A. Hervieux
Phys. Rev. B 84, 172407 (2011)

Relaxation times for isolated NPs (circles) and interacting NPs for different interparticle distances: d = 9.6 nm (squares), d = 11.8 nm (triangles), and d =16.6 nm (stars). The occupation probability is p = 0.5. The damping constant is α = 1.

Finite-size effect on Tc of Ni NPs

Finite-size scaling behavior and intrinsic critical exponents of nickel: Comparison with the three-dimensional Heisenberg model.
Jun Wang, Wei Wu, Fan Zhao, and Guo-meng Zhao
Phys. Rev. B 84, 174440 (2011)

(a) Plot of T_C versus the mean diameter of the Ni NPs. The best fit yields ν = 1.06 ±0.07 and ξ0 = 0.65 ± 0.10 nm. (b) Same for Ni nanowires. The best fit yields ν = 1.03 ± 0.05 and ξ0 = 2.4 ± 0.4 nm.

Lage self-assemblies of NPs

Ultra-Large-Area Self-Assembled Monolayers of Nanoparticles.
Tianlong Wen and Sara A. Majetich
ACS Nano 5, 8868 (2011)

Ab initio couplings in Fe

Magnetoelastic coupling in gamma-iron.
S. V. Okatov, Yu. N. Gornostyrev, A. I. Lichtenstein, M. I. Katsnelson
ArXiv 1111.4432 (2011)

The exchange parameter as a function of interatomic distance to the n-th neighbour Jn(Rn) for different c/a ratios.

Effect of current on energy barrier for DW pinning

Electric Current Effect on the Energy Barrier of Magnetic DomainWall Depinning: Origin of the Quadratic Contribution.
Kab-Jin Kim, Jisu Ryu, Gi-Hong Gim, Jae-Chul Lee, Kyung-Ho Shin, Hyun-Woo Lee, and Sug-Bong Choe
Phys. Rev. Lett. 107, 217205 (2011)

(a) Two-dimensional map of E_B as a function of H and J. (b) E_B vs J at several bias H. The solid lines are the best fit with Eq. (2).

Magnetic and structural order in Mn3O4

Pressure and field tuning the magnetostructural phases of Mn3O4: Raman scattering and x-ray diffraction studies.
M. Kim, X. M. Chen, X. Wang, C. S. Nelson, R. Budakian, P. Abbamonte, and S. L. Cooper
Phys. Rev. B 84, 174424 (2011)

Contour plots of the T2g(1) phonon mode intensities as functions of energy and field (e) Illustrations of theMn3O4 structure in (I) the orthorhombicwithmagnetic easy axis along [110], (II) tetragonal, and (III) orthorhombic structure of Mn3O4 with magnetic easy axis along [110]. (f) H-T phase diagram.

Control of damping with metamaterials

Control of Gilbert damping using magnetic metamaterials.
Chiharu Mitsumata, Satoshi Tomita
Phys. Rev. B 84, 174421 (2011)

Comparison between Model 2 (green line and blue circles) and Model 3 (pink line and red triangles) when
r0 = 10. Effective Gilbert damping factor α  is obtained from the fitting curves.

Magnon damping from DFT

Different dimensionality trends in the Landau damping of magnons in iron, cobalt, and nickel: Time-dependent density functional study.
Paweł Buczek, Arthur Ernst, and Leonid M. Sandratskii
Phys. Rev. B 84, 174418 (2011)

Spin waves of fcc Co. Solid circles correspond to ω0(q), while the error bars denote full width at  half maximum (FWHM) of the peak. Solid line denotes SW energies obtained from MFT. Solid triangles stand for the experimental estimation of the dispersion relation by Balash.

TM oxides by ab initio DFT calculations

Magnon spectrum of transition-metal oxides: Calculations including long-range magnetic interactions using the LSDA + U method.
F. Essenberger, S. Sharma, J. K. Dewhurst, C. Bersier, F. Cricchio, L. Nordström, and E. K. U. Gross
Phys. Rev. B 84, 174425 (2011)

N´eel temperatures as a function of U for NiO, CoO, and MnO. The dashed lines denote the experimental values and the gray solid lines are Monte Carlo simulations.

Magnetoelastic metamaterials

Magnetoelastic metamaterials.
Mikhail Lapine, Ilya V. Shadrivov, David A. Powell and Yuri S. Kivshar
Nature Mater. 11,30 (2011)

An anisotropic magnetic metamaterial combined with an elastic medium. wo layers of the bulk sample are shown. a, The metamaterial before the electromagnetic field is applied. b, The metamaterial is compressed by the electromagnetic forces acting between the elements. Dimensionless lattice parameters a and bare normalized to the resonator radius r₀.