Switching NPs by microwaves

Optimal switching of a nanomagnet assisted by microwaves.
N. Barros, M. Rassam, H. Jirari, and H. Kachkachi
Phys Rev. B 83, 144418 (2011)

Optimized MWfield (upper panel) and the corresponding spin trajectories (lower panel). The inset is a 3D plot
of the spin trajectory on the unit sphere.

Fingerprinting Antiferromagnetic structures

Fingerprinting the magnetic behavior of antiferromagnetic nanostructures using remanent magnetization curves.
M. J. Benitez, O. Petracic, H. Tüysüz, F. Schüth, and H. Zabel
Phys. Rev. B 83, 134424 (2011)

TRM and IRM vs H of (a) the SG system
AuFe(0.5%) adapted from Ref. 46, (b) of SPM Fe particles, with a
mean diameter of 3 nm embedded in alumina adapted from Ref. 47,
(c) of theDAFF systemFe0.48Zn0.52Fe, adapted from Ref. 30, (d) and
of Co3O4 nanowires (NWs) at 5 K adapted from Ref. 9.

Spin valve MR induced by an AFM

A spin-valve-like magnetoresistance of an antiferromagnet-based tunnel junction.
B. G. Park1, J.Wunderlich, X. Martí, V. Holý, Y. Kurosaki, M. Yamada, H. Yamamoto,
A. Nishide, J. Hayakawa, H. Takahashi1, A. B. Shick and T. Jungwirth.
Nature Mater. 10, 347 (2011), News & Views: Nature Mater. 10, 344 (2011)  

A spin-valve-like signal in the NiFe/IrMn(1.5 nm)/MgO/Pt AFM tunnel device compared with the weak magnetoresistance of an FM NiFe/MgO/Pt tunnel junction.

Magnetic vortex core reversal by excitation of spin waves

Magnetic vortex core reversal by excitation of spin waves.
Matthias Kammerer, Markus Weigand, Michael Curcic, Matthias Noske, Markus Sproll, Arne Vansteenkiste, Bartel Van Waeyenberge, Hermann Stoll, Georg Woltersdorf, Christian H. Back & Gisela Schuetz
Nature Comms 2, 279 (2011)

The legend (c) shows microscopy images of X-ray transmission through the inner part (150 nm×150 nm) of the sample indicating the vortex core polarity (white: vortex up; black: vortex down) before and after a field burst. The phase diagrams show the points (excitation amplitude versus frequency) where vortex core reversal from up to down was observed in the experiments (a) and the simulations (b).

Ultrafast reversal of antiferromagnetically coupled spins

Transient ferromagnetic-like state mediating ultrafast reversal of antiferromagnetically coupled spins.
I. Radu, K. Vahaplar, C. Stamm, T. Kachel, N. Pontius, H. A. Dürr, T. A. Ostler, J. Barker, R. F. L. Evans, R. W. Chantrell,A. Tsukamoto, A. Itoh, A. Kirilyuk, Th. Rasing and A. V. Kimel
 Nature 472, 205 (2011)

Element-resolved dynamics of the Fe and Gd magnetic moments measured by time-resolved XMCD with femtosecond time-resolution.

Ground State in artificial square ice

Thermal ground-state ordering and elementary excitations in artificial magnetic square ice.
Jason P. Morgan, Aaron Stein, Sean Langridge, Christopher H. Marrows
Nature Physics 7, 68 (2011)

a, Direct observation of frozen-in long-range GS order with ~10-μm-width domains, separated by antiferromagnet-like DW boundaries, supporting localized elementary excitations of small groups of moments flipped against the background. A magnified region, containing a DW and localized excitations (1, 2L, 3Z, notation explained in the text), is shown in the inset. A key identifying the rotationally degenerate vertex configurations is also shown. The green square indicates a large domain-like excitation. b, Moment arrangements of the regions highlighted in a, indicating the flipped elements (grey), T₂-dipole (green arrow) and T₃-monopole vertices (red and blue circles) making up the defects.

Magnetic monopoles in spin ice

Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice.
Elena Mengotti, Laura J. Heyderman , Arantxa Fraile Rodríguez , Frithjof Nolting , Remo V. Hügli , Hans-Benjamin Braun
Nature Physics 7, 68 (2011)

a, Schematic view of the nanolithographic array of permalloy islands with anisotropy axes along honeycomb links and the orientation of the magnetization indicated by arrows. . b, Corresponding charge distribution with magnetic moments replaced by dumbbells carrying charge q and −q (in red and blue).

Vortex-Core Reversal

Edge-Soliton-Mediated Vortex-Core Reversal Dynamics
Ki-Suk Lee, Myoung-Woo Yoo, Youn-Seok Choi, and Sang-Koog Kim
Phys. Rev. Lett. 106, 147201 (2011)

Comparison of two different dynamic
behaviors associated with two coupled edge solitons: (a) in-plane
persistent rotation of two edge solitons at disk boundary and
(b) transformation to VC of reversed orientation.

Magnetic nanoparticles with bulklike properties

Magnetic nanoparticles with bulklike properties

Xavier Batlle, N. Pérez, P. Guardia, O. Iglesias, A. Labarta, F. Bartolomé, L. M. García, J. Bartolomé, A. G. Roca, M. P. Morales, and C. J. Serna

J. Appl. Phys. 109, 07B524 (2011).

Magnetization curves at 5 K for Fe_3−xO₄ NPs about 5 nm in size obtained by thermal decomposition (dashed lines) or coprecipitation (solid lines). The closures of the hysteresis loops are indicated by vertical arrows. Inset: detail of the curves for magnetic fields below 6 kOe.

Toroidal Ferroelectricitity in PbTiO_{3} Nanoparticles

Toroidal Ferroelectricitity in PbTiO_{3} Nanoparticles
M. G. Stachiotti and M. Sepliarsky
Phys. Rev. Lett. 106, 137601 (2011)

(a) Pz polarization mapfor a 20x20x20 nanodot at T ¼ 50 K. (b) Vortexlike structure of the local polarizations in a 20x20x20 nanoparticle. The arrows give the direction of the projected displacement along the yz plane, and the arrow length indicates the projectedmagnitude. (c) Temperature dependence of the modulus of the
toroidal moment for several cubic nanodots.

Diluted Magnetic Semiconductors

Nearly non-magnetic valence band of the ferromagnetic semiconductor GaMnAs
Shinobu Ohya, Kenta Takata, and Masaaki Tanaka
Nature Physics 7, 342 (2011).

Physical properties of elongated inorganic nanoparticles

Physical properties of elongated inorganic nanoparticles.

Roman Krahne, Giovanni Morello, Albert Figuerola, Chandramohan George, Sasanka Deka and Liberato Manna
Physics Reports 501, 75 (2011)

(A-I) Gold nanorods of various aspect ratios. (J) UV–visible spectra of the samples. (K) Geometrical factors for axially symmetric ellipsoids as a function of the aspect ratio. (L) Curve correlating the plasmon resonance conditions as a function of the geometrical factor in a spheroidal particle.

Observation of imprinted AF vortex states

Direct observation of imprinted antiferromagnetic vortex states in CoO/Fe/Ag(001) discs

J.Wu, D. Carlton, J. S. Park, Y. Meng, E. Arenholz, A. Doran, A. T. Young, A. Scholl, C. Hwang, H.W. Zhao, J. Bokor and Z. Q. Qiu
Nature Physics 7,303 (2011)