Frustration in artificial spin ice

The unhappy wanderer.
R. L. Stamps
Nature Physics 10, 623 (2014)

Emergent ice rule and magnetic charge screening from vertex frustration in artificial spin ice.

Ian Gilbert, Gia-Wei Chern, Sheng Zhang, Liam O’Brien, Bryce Fore,, Cristiano Nisoli and Peter Schi effer

Nature Physics 10, 670 (2014)

An initial spin (green) is placed arbitrarily on an empty lattice. A second spin is placed on a neighbouring lattice segment in a direction parallel to the first, unless the spins share a vertex, in which case the direction of the spin reverses (if the vertex is traversed in a straight line) or rotates (if a turn is taken). Subsequent spins placed in the same way eventually reach the starting position and close the loop (red). A lattice is considered 'happy' (a) when these rules can be obeyed at every segment along the loop, and 'unhappy' or vertex-frustrated (b) when they fail.

Artificial Frustrated Systems

Focus on artificial frustrated systems.
J Cumings, L J Heyderman, C H Marrows and R L Stamps
New J. Phys. 16, 075016 (2014)

Artificial spin ices. (a) XMCD-PEEM image of artificial spin ice, captured in the so-called 'string regime' [7], while undergoing thermal relaxation from an energetically excited, saturated moment, configuration down to one of the two degenerate ground states. Nanomagnets with moments pointing towards the bottom/left appear in blue contrast, while nanomagnets with moments pointing up/right appear in red contrast. Scale bar 2 μm. (b) X-ray transmission micrograph of a CoFeB artificial square ice with the overlaid red gridlines showing the square lattice. Magnetic contrast is shown in the inset, where islands that have reversed under thermal excitation at 100 °C appear with bright contrast. Scale bar 1 μm. (c) Lorentz transmission electron micrograph of artificial kagome ice after thermal excitation. The magnetization direction within the arms of the array can be determined from the detailed intensity profile across the arm [8], allowing the magnetic charge at each vertex to be inferred. Positive and negative magnetic charges are indicated by the overlaid red and blue dots, showing that the sample is in the charge-ordered, kagome ice-II state. Scale bar 500 nm. (d) The number of configurations that can be created in an artificial square ice by an applied field is very sensitive to disorder. The diagram represents all possible configurations that can be realized by application of the field (with magnitude slightly larger than the mean coercive field) to sixteen elements starting from a saturated type II state with a distribution of switching fields. Each unique configuration is indicated by a circular dot

Modeling vortices in nanodisks by simulations

I have compiled a collection of articles from the Brazilian group of B. V. Costa and collegues on the subject of simulation of vortex structures on nanodots. I hope they will be of interest to you:

Analytical and Monte Carlo study of two antidots in magnetic nanodisks
with vortex-like magnetization
A. R. Pereira, A. R. Moura, W. A. Moura-Melo, D. F. Carneiro, S. A. Leonel and P. Z. Coura
J. Appl. Phys. 101, 034310 (2007)

A model for vortex formation in magnetic nanodots
S. A. Leonel, I. A. Marques, P. Z. Coura, and B. V. Costa
J. Appl. Phys. 102, 104311 (2007)

Diagram for vortex formation in quasi-two-dimensional magnetic dots
J. C. S. Rocha, P. Z. Coura, S. A. Leonel, R. A. Dias, and B. V. Costa
J. Appl. Phys. 107, 053903 (2010)

Magnetic vortex formation and gyrotropic mode in nanodisks.
D. Toscano, S. A. Leonel, R. A. Dias, P. Z. Coura, J. C. S. Rocha  and B. V. Costa
J. Appl. Phys. 109, 014301 (2011)

Artificial Frustrated Systems

The New Journal of Physics has opened a new Focus section on Artificial Frustrated Systems edited by
John Cumings, Laura Jane Heyderman, Christopher Marrows, Robert Stamps 
Focus on Artificial Frustrated Systems

The special section includes a growing collection of articles that will be published during 2012. Up to now it includes  the following:

Gibbsianizing nonequilibrium dynamics of artificial spin ice and other spin systems
Paul E Lammert, Vincent H Crespi and Cristiano Nisoli 
2012 New J. Phys. 14 045009

A network model for field and quenched disorder effects in artificial spin ice
 Zoe Budrikis, Paolo Politi and R L Stamps2012 New J. Phys. 14 045008

Dynamics of artificial spin ice: a continuous honeycomb network 
Yichen Shen, Olga Petrova, Paula Mellado, Stephen Daunheimer, John Cumings and Oleg Tchernyshyov 
2012 New J. Phys. 14 035022

On thermalization of magnetic nano-arrays at fabrication 
Cristiano Nisoli
 2012 New J. Phys. 14 035017
 

Magnetic dipole configurations in honeycomb lattices: order and disorder 
Alexandra Schumann, Philipp Szary, Elena Y Vedmedenko and Hartmut Zabel
2012 New J. Phys. 14 035015

Domain dynamics and fluctuations in artificial square ice at finite temperatures 
Z Budrikis, K L Livesey, J P Morgan, J Akerman, A Stein, S Langridge, C H Marrows and R L Stamps
2012 New J. Phys. 14 035014

Melting artificial spin ice
 Vassilios Kapaklis, Unnar B Arnalds, Adam Harman-Clarke, Evangelos Th Papaioannou, Masoud Karimipour, Panagiotis Korelis, Andrea Taroni, Peter C W Holdsworth, Steven T Bramwell and Björgvin Hjörvarsson
2012 New J. Phys. 14 035009

Multi-step ordering in kagome and square artificial spin ice 
C J Olson Reichhardt, A Libál and C Reichhardt
2012 New J. Phys. 14 025006

Thermodynamics of elementary excitations in artificial magnetic square ice 
R C Silva, F S Nascimento, L A S Mól, W A Moura-Melo and A R Pereira
2012 New J. Phys. 14 015008

Magnetic reversal of an artificial square ice: dipolar correlation and charge ordering 
J P Morgan, A Stein, S Langridge and C H Marrows
2011 New J. Phys. 13 105002

Metallic nanodumbbells

Study of Nucleation and Growth Mechanism of the Metallic Nanodumbbells.
Galyna Krylova, Lisandro J. Giovanetti, Felix G. Requejo, Nada M. Dimitrijevic, Alesia Prakapenka,and Elena V. Shevchenko
JACS 134, 4384 (2012)

Reversal of individual Co islands

Magnetization Reversal of Individual Co Nanoislands.
S. Ouazi, S. Wedekind, G. Rodary, H. Oka, D. Sander, and J. Kirschner
Phys. Rev. Lett. 108, 107206 (2012)

Island size dependence of the energy barrier Delta E. (a) The blue curve is a linear fit Delta E_lin=K(N-N0)The red curve shows the calculated energy barrier for domain wall formation Delta E_dw= 4 sigma sqrt(AK).
.

Ferroelectric solid state memories

Solid-state memories based on ferroelectric tunnel junctions.
André Chanthbouala, Arnaud Crassous, Vincent Garcia, Karim Bouzehouane, Stéphane Fusil, Xavier Moya, Julie Allibe, Bruno Dlubak, Julie Grollier, Stéphane Xavier, Cyrile Deranlot, Amir Moshar, Roger Proksch, Neil D. Mathur, Manuel Bibes and Agnés Barthélémy
Nature Nanotechn. 7, 101 (2012)

Ferroelectric switching versus resistive switching. a,b, Out-ofplane PFM phase (a) and amplitude (b) measurements on a typical gold/cobalt/BTO/LSMO ferroelectric tunnel junction. c, R(Vwrite) for a similar capacitor measured in remanence (Vread¼100 mV) after applying successive voltage pulses of 100 ms. The open and filled circles represent two different scans to show reproducibility.

Nanoelectronics: Ferroelectric devices show potential.
Adrian M. Ionescu
Nature Nanotechn. 7, 83 (2012)

The ferroelectric tunnel junction as a non-volatile memory cell.

Size dependence of Exchange Bias

Size Dependence of Exchange Bias in Co/CoO Nanostructures
Sara Laureti, Sarah Y. Suck, Helge Haas, Eric Prestat, Olivier Bourgeois, and Dominique Givord
Phys. Rev. Lett. 108, 077205 (2012)

Temperature dependence of Heb in Co/CoO/Au samples measured for the three nanostructure sizes S (squares), M (dots), and L (triangles).

Meron-like magnetic order in coupled discs

Direct Observation of Unconventional Topological Spin Structure in Coupled Magnetic Discs.
C. Phatak, A. K. Petford-Long, and O. Heinonen
Phys. Rev. Lett. 108, 067205 (2012)

(a) Schematic showing the spin structure of a meronlike state with opposite chirality; (b) schematic showing the trilayer discs and direction of the electron beam for imaging, and (c) LTEM under-focus image, and (d) reconstructed magnetic induction color map.

Dynamics in rectangular elements

Magnetization dynamics and cone angle precession in permalloy rectangles.
Nils Kuhlmann, Andreas Vogel, and Guido Meier
Phys. Rev. B 85, 014410 (2012)

Em field distribution in a nanodisk

Probing the Electromagnetic Field Distribution within a Metallic Nanodisk.
David Meneses-Rodríguez , Elías Ferreiro-Vila , Patricia Prieto, José Anguita , María U. González , José M. García-Martín , Alfonso Cebollada, Antonio García-Martín, and Gaspar Armelles
Small 7, 3317 (2011)

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.

TMR modulation in single nanoislands

Spatially Modulated Tunnel Magnetoresistance on the Nanoscale.
Hirofumi Oka, Kun Tao, Sebastian Wedekind, Guillemin Rodary, Valeri S. Stepanyuk, Dirk Sander, and Jü rgen Kirschner
Phys. Rev. Lett. 107, 187201 (2011)

Maps of the TMR ratio obtained at the indicated voltages(e)–(g) Line profiles, averaged over 6
adjacent lines for an improved signal-to-noise ratio, of the TMR ratio images along the yellow arrows in (b)–(d).

Rectangular an rhombic dipolar lattices

Magnetization processes in rectangular versus rhombic planar superlattices of magnetic bars.
Y. G. Pogorelov, G. N. Kakazei, J. M. Teixeira, A. Hierro-Rodriguez, F. Valdés-Bango, M. Vélez, J. M. Alameda, J. I. Martín, J. Ventura, and J. B. Sousa
Phys. Rev. B 84, 052402 (2011)

Remagnetization processes at sweeping from positive to negative applied field for rec- (a)–(d) and rho- (e)–(h) superlattice geometries. Inverted areas in each case are outlined and shadowed.

Review on Magnetic nanostructures

Magnetic nanostructures for advanced technologies: fabrication, metrology and challenges.
June W Lau and Justin M Shaw
J. Phys. D 44, 303001 (2011)

X-Ray Diffraction Microscopy of Magnetic Structures

X-Ray Diffraction Microscopy of Magnetic Structures.
Joshua J. Turner, Xiaojing Huang, Oleg Krupin, Keoki A. Seu, Daniel Parks, Stephen Kevan, Enju Lima, Kim Kisslinger, Ian McNulty, Richard Gambino, Stephane Mangin, Sujoy Roy, and Peter Fischer
PRL 107, 033904 (2011)