Tension-free Dirac strings and steered magnetic charges in 3D artificial spin ice

Abstract 3D nano-architectures present a new paradigm in modern condensed matter physics with numerous applications in photonics, biomedicine, and spintronics. They are promising for the realisation of 3D magnetic nano-networks for ultra-fast and low-energy data storage. Frustration in these systems can lead to magnetic charges or magnetic monopoles, which can function as mobile, binary information carriers. However, Dirac strings in 2D artificial spin ices bind magnetic charges, while 3D dipolar counterparts require cryogenic temperatures for their stability. Here, we present a micromagnetic study of a highly-frustrated 3D artificial spin ice harboring tension-free Dirac strings with unbound magnetic charges at room temperature. We use micromagnetic simulations to demonstrate that the mobility threshold for magnetic charges is by 2 eV lower than their unbinding energy. By applying global magnetic fields, we steer magnetic charges in a given direction omitting unintended switchings. The introduced system paves a way towards 3D magnetic networks for data transport and storage.

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Tension-free Dirac strings and steered magnetic charges in 3D artificial spin ice

npj Computational Materials ◽

10.1038/s41524-021-00593-7 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Sabri Koraltan ◽

Florian Slanovc ◽

Florian Bruckner ◽

Cristiano Nisoli ◽

Andrii V. Chumak ◽

...

Keyword(s):

Data Storage ◽

Magnetic Monopoles ◽

Data Transport ◽

Spin Ice ◽

New Paradigm ◽

Micromagnetic Simulations ◽

Tension Free ◽

Artificial Spin Ice ◽

Binary Information ◽

And Storage

Abstract3D nano-architectures presents a new paradigm in modern condensed matter physics with numerous applications in photonics, biomedicine, and spintronics. They are promising for the realization of 3D magnetic nano-networks for ultra-fast and low-energy data storage. Frustration in these systems can lead to magnetic charges or magnetic monopoles, which can function as mobile, binary information carriers. However, Dirac strings in 2D artificial spin ices bind magnetic charges, while 3D dipolar counterparts require cryogenic temperatures for their stability. Here, we present a micromagnetic study of a highly frustrated 3D artificial spin ice harboring tension-free Dirac strings with unbound magnetic charges at room temperature. We use micromagnetic simulations to demonstrate that the mobility threshold for magnetic charges is by 2 eV lower than their unbinding energy. By applying global magnetic fields, we steer magnetic charges in a given direction omitting unintended switchings. The introduced system paves the way toward 3D magnetic networks for data transport and storage.

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Artificial kagome spin ice: dimensional reduction, avalanche control and emergent magnetic monopoles

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0538 ◽

2012 ◽

Vol 370 (1981) ◽

pp. 5767-5782 ◽

Cited By ~ 26

Author(s):

R. V. Hügli ◽

G. Duff ◽

B. O'Conchuir ◽

E. Mengotti ◽

A. Fraile Rodríguez ◽

...

Keyword(s):

Data Storage ◽

Dimensional Reduction ◽

Magnetic Monopoles ◽

Real Space ◽

Model Systems ◽

Dimensional System ◽

Two Dimensional ◽

Spin Ice ◽

Artificial Spin Ice ◽

String Formation

Artificial spin-ice systems consisting of nanolithographic arrays of isolated nanomagnets are model systems for the study of frustration-induced phenomena. We have recently demonstrated that monopoles and Dirac strings can be directly observed via synchrotron-based photoemission electron microscopy, where the magnetic state of individual nanoislands can be imaged in real space. These experimental results of Dirac string formation are in excellent agreement with Monte Carlo simulations of the hysteresis of an array of dipoles situated on a kagome lattice with randomized switching fields. This formation of one-dimensional avalanches in a two-dimensional system is in sharp contrast to disordered thin films, where avalanches associated with magnetization reversal are two-dimensional. The self-organized restriction of avalanches to one dimension provides an example of dimensional reduction due to frustration. We give simple explanations for the origin of this dimensional reduction and discuss the disorder dependence of these avalanches. We conclude with the explicit demonstration of how these avalanches can be controlled via locally modified anisotropies. Such a controlled start and stop of avalanches will have potential applications in data storage and information processing.

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Magnetic dipole configurations on honeycomb lattices: effect of finite size and boundaries

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2011.0401 ◽

2012 ◽

Vol 370 (1981) ◽

pp. 5783-5793 ◽

Cited By ~ 2

Author(s):

Alexandra Schumann ◽

Hartmut Zabel

Keyword(s):

Magnetic Field ◽

Boundary Conditions ◽

Magnetic Dipole ◽

Finite Size ◽

Magnetic Monopoles ◽

Spin Ice ◽

Artificial Spin Ice

Artificial dipolar spin-ice patterns have attracted much attention recently because of their rich configurations and excitations in the form of Dirac strings connecting magnetic monopoles. We have analysed the distribution of excitations in the form of strings and vertices carrying magnetic charges Q =±3 q in honeycomb artificial spin-ice patterns. Two types of patterns are compared, those that terminate with open hexagons and those with closed hexagons. The dipole configurations and the frequency of spin-ice rule-violating Q =±3 q vertices depend slightly on the boundary conditions of the pattern. Upon rotation of the patterns by 2 π in a coercive magnetic field of 500 Oe, complete reversibility of the charge and string configuration is observed.

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Thermally and field-driven mobility of emergent magnetic charges in square artificial spin ice

Scientific Reports ◽

10.1038/s41598-019-52460-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Sophie A. Morley ◽

Jose Maria Porro ◽

Aleš Hrabec ◽

Mark C. Rosamond ◽

Diego Alba Venero ◽

...

Keyword(s):

Critical Field ◽

Magnetic Monopoles ◽

Model Systems ◽

Square Lattice ◽

Creep Model ◽

Spin Ice ◽

One Dimensional ◽

X Ray ◽

Drift Motion ◽

Artificial Spin Ice

Abstract Designing and constructing model systems that embody the statistical mechanics of frustration is now possible using nanotechnology. We have arranged nanomagnets on a two-dimensional square lattice to form an artificial spin ice, and studied its fractional excitations, emergent magnetic monopoles, and how they respond to a driving field using X-ray magnetic microscopy. We observe a regime in which the monopole drift velocity is linear in field above a critical field for the onset of motion. The temperature dependence of the critical field can be described by introducing an interaction term into the Bean-Livingston model of field-assisted barrier hopping. By analogy with electrical charge drift motion, we define and measure a monopole mobility that is larger both for higher temperatures and stronger interactions between nanomagnets. The mobility in this linear regime is described by a creep model of zero-dimensional charges moving within a network of quasi-one-dimensional objects.

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Chiral nature of magnetic monopoles in artificial spin ice

New Journal of Physics ◽

10.1088/1367-2630/15/3/035026 ◽

2013 ◽

Vol 15 (3) ◽

pp. 035026 ◽

Cited By ~ 28

Author(s):

N Rougemaille ◽

F Montaigne ◽

B Canals ◽

M Hehn ◽

H Riahi ◽

...

Keyword(s):

Magnetic Monopoles ◽

Spin Ice ◽

Artificial Spin Ice

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Emergent magnetic monopole dynamics in macroscopically degenerate artificial spin ice

Science Advances ◽

10.1126/sciadv.aav6380 ◽

2019 ◽

Vol 5 (2) ◽

pp. eaav6380 ◽

Cited By ~ 40

Author(s):

Alan Farhan ◽

Michael Saccone ◽

Charlotte F. Petersen ◽

Scott Dhuey ◽

Rajesh V. Chopdekar ◽

...

Keyword(s):

Magnetic Monopole ◽

Topological Defects ◽

Magnetic Monopoles ◽

Real Space ◽

Spin Ice ◽

Solid State Physics ◽

Pinch Point ◽

Topological Excitations ◽

Artificial Spin Ice ◽

Hückel Theory

Magnetic monopoles, proposed as elementary particles that act as isolated magnetic south and north poles, have long attracted research interest as magnetic analogs to electric charge. In solid-state physics, a classical analog to these elusive particles has emerged as topological excitations within pyrochlore spin ice systems. We present the first real-time imaging of emergent magnetic monopole motion in a macroscopically degenerate artificial spin ice system consisting of thermally activated Ising-type nanomagnets lithographically arranged onto a pre-etched silicon substrate. A real-space characterization of emergent magnetic monopoles within the framework of Debye-Hückel theory is performed, providing visual evidence that these topological defects act like a plasma of Coulomb-type magnetic charges. In contrast to vertex defects in a purely two-dimensional artificial square ice, magnetic monopoles are free to evolve within a divergence-free vacuum, a magnetic Coulomb phase, for which features in the form of pinch-point singularities in magnetic structure factors are observed.

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