Skyrmion lattice and helimagnetism in Cu2OSeO3

Long wavelength helimagnetic order and skyrmion lattice phase in Cu2OSeO3.
T. Adams, A. Chacon, M. Wagner, A. Bauer, G. Brandl, B. Pedersen, H. Berger, P. Lemmens, and C. Pffeiderer
ArXiv 1204.3597 (2012)

Magnetic phase diagram of Cu2OSeO3 as a function of applied magnetic field for various
orientations inferred from the magnetisation. (a) Overview for eld parallel h111i. Panels (b) through (d): Phase diagram
in the vicinity of Tc for various orientations. Di fferences as a function of eld are mostly due to demagnetising e ffects;
the brown shading indicates the regime of nearly critical spin fluctuations.

Magnetization distribution in an FeO NP by SANS

Quantitative spatial magnetization distribution in iron oxide nanocubes and nanospheres by polarized small-angle neutron scattering.
S Disch1, E Wetterskog, R P Hermann, A Wiedenmann,U Vainio, G Salazar-Alvarez, L Bergström and Th Brücke
New Journal of Physics 14, 013025 (2012)

Purely nuclear SANS of spherical and cubic nanoparticles (scaled by 0.5 for display). Lines indicate fits to the model depicted in the right inset. Left inset: 10 deg sectors used for integrating the two-dimensional (2D) scattering.

Neutron study of canted domains

Specular and off-specular polarized neutron reflectometry of canted magnetic domains in loose spin coupled CuMn/Co multilayers.
T. Saerbeck,, N. Loh, D. Lott, B. P. Toperverg, A. M. Mulders, M. Ali, B. J. Hickey,A. P. J. Stampfl, F. Klose, and R. L. Stamps
Phys. Rev. B 85, 014411 (2012)

See also the related entry: http://nanomagn.blogspot.com/2011/09/mapping-loose-spin-rkky-coupling.html

(a) Field dependence of the coupling angle 2 Dalta γ in the sample with 19 A° Cu0.94Mn0.06 (lines are a guide to the eye). (b) Temperature dependence of J1 and J2 reproduced from.8 the lines in (b) are fits obtained from the model reported by Saerbeck et al.

Modeling of NP SANS by micromagnetics

Micromagnetic modeling and small-angle neutron scattering characterization of magnetic nanocomposites.
Sergey Erokhin, Dmitry Berkov, Nataliya Gorn, and Andreas Michels
Phys. Rev. B 85, 024410 (2012)

Comparison of the SANS intensities obtained experimentally (Exp., upper row) and simulated numerically
(Num. sim., lower row) for different external fields as indicated (a logarithmic scale for the intensities was used).

Exchange interparticle interactions in Fe oxides

Spin reorientation in α-Fe2O3 nanoparticles induced by interparticle exchange interactions in α-Fe2O3/NiO nanocomposites.
C. Frandsen, K. Lefmann, B. Lebech, C. R. H. Bahl, E. Brok, S. N. Ancoña, L. Theil Kuhn, L. Keller,T. Kasama, L. C. Gontard, and S. Mørup
Phys. Rev. B 84, 214435 (2011)

Mössbauer spectra of 8-nm α-Fe2O3 nanoparticles obtained at the indicated temperatures; (a) ferrofluid sample, (b)
powder sample, and (c) mixed with NiO nanoparticles

Diluted AF/FM interfacial coupling

Interfacial coupling between ferromagnets and random and dilute antiferromagnets.
Kineshma Munbodh, Miyeon Cheon, and David Lederman, M. R. Fitzsimmons, Neil R. Dilley

Phys. Rev. B 84, 214434 (2011)

(a) Depth profile of the magnetization
from the PNR data at T = 5 K. The magenta dashed curve and solid
green curve correspond to H = +6.5 and −6.5 kOe, respectively. (b)
Depth profile of the pinned and unpinned magnetizations (solid blue
and dashed red curves, respectively) calculated for H = −6.5 kOe
with respect to H = +6.5 kOe. The vertical dotted lines indicate
the position of the interfaces, with the substrate-film interface set to
z = 0.

Mapping loose spin RKKY coupling

Spatial Fluctuations of Loose Spin Coupling in CuMn/Co Multilayers.
T. Saerbeck, N. Loh, D. Lott, B. P. Toperverg, A. M. Mulders, A. Fraile Rodrıíguez, J.W. Freeland, M. Ali, B. J. Hickey, A. P. J. Stampfl, F. Klose, and R. L. Stamps
Phys. Rev. Lett. 107, 127201 (2011)

(a) Schematic coupling of a PM Mn spin between two FM layers. (b) Calculated lateral variation of J_LSC at 30 K. (c) RKKY exchange fields acting on loose Mn atoms derived by fits to the experimental data. Black dots indicate (111) planes in the fcc lattice. The extended plateau on either side of the plot indicates Mn impurities in the direct vicinity of the Co layers experiencing direct magnetic exchange.

Excitations in Core/shell NPs

Low-energy magnetic excitations in Co/CoO core/shell nanoparticles.
M. Feygenson, X. Teng, S. E. Inderhees, Y. Yiu, W. Du, W. Han, J. Wen, Z. Xu, A. A. Podlesnyak, J. L. Niedziela, M. Hagen, Y. Qiu, C. M. Brown, L. Zhang, and M. C. Aronson.
Phys. Rev. B 83, 174414 (2011)

(a) The q-integrated scattered intensity I (E) at different temperatures for Co/CoO nanoparticles. Dashed lines indicate the onset of antiferromagnetic order at TN and the dynamical blocking of the Co cores at the blocking temperature
TB. (b) Energy dependence of χ(E) for a constant wave-vector cut 0.12 °A−1 wide and centered at q = 1.27 °A−1 (c) The scattered intensity I (q,E) at 150 K. Dark curved lines are shadows from the radial collimator.