Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice

Mengotti, E.; Heyderman, Laura J.; Rodríguez, A. Fraile; Nolting, F.; Hügli, Remo V.; Braun, Hans‐Benjamin

doi:10.1038/nphys1794

Cited by 404 publications

(530 citation statements)

References 39 publications

Supporting

Mentioning

508

Contrasting

Unclassified

Order By: Relevance

“…Being in stark contrast to the standard nucleation in two-dimensional films [14], the observed behaviour provides a novel example of dimensional reduction [15,16] due to the frustrating effect of the dipolar interactions together with non-collinear anisotropies. After a brief discussion of the experimental results [17], we shall show that they are in excellent agreement with Monte Carlo (MC) simulations of point dipoles on a kagome lattice. We provide statistical evidence of the one-dimensional nature of the avalanches and demonstrate numerically that the dimensional reduction persists even in the limit of extremely low disorder, a limit that is experimentally unattainable.…”

Section: Introductionmentioning

confidence: 60%

“…large switching fields) that will stop the avalanche at a certain value of the applied field and hence prevent unlimited string growth with the monopoles accumulating at the edge of the sample. Note also that the monopoles only remain freely mobile until they reach another string and are trapped there [17]. In figure 3c, the mobile monopole density is shown as a fraction of all available honeycomb sites, with a clear peak around the coercive field H c .…”

Section: Resultsmentioning

confidence: 99%

“…This latter term plays the role of a charging energy or Hubbard-like on-site charge repulsion. The quantitative value for v 0 may be determined via matching the charge interaction of two neighbouring dumbbells with the dipolar interaction [8] or it may be evaluated directly via the micromagnetic interaction between the surface charges of the semicircular ends of two adjacent islands [17,24]. Equation (2.2) has several important consequences.…”

Section: Artificial Kagome Spin-ice Systemmentioning

confidence: 99%

“…As is evident from figure 2, these defects reside at the ends of this string, carry charge DQ a /q = ±2 and they remain defects in an averaged, 'smeared' charge densitỹ r m . Since these defects are freely mobile at small fields, they act as emergent monopole quasiparticles [17].…”

Section: Artificial Kagome Spin-ice Systemmentioning

confidence: 99%

See 3 more Smart Citations

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

Hügli

Duff

O'Conchuir

et al. 2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

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 synchrotronbased 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 twodimensional. 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.

show abstract

Section: Introductionmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Section: Artificial Kagome Spin-ice Systemmentioning

confidence: 99%

Section: Artificial Kagome Spin-ice Systemmentioning

confidence: 99%

See 2 more Smart Citations

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

Hügli

Duff

O'Conchuir

et al. 2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

show abstract

“…The propagation of these spin flips can be extended in the crystal, generating a system whose physical image can be represented as similar to Dirac-like strings in which the corresponding poles do not practically suffer any mutual interaction. However, the strings in these spin-ices are theoretically observable [20] and experimentally observed [21], and this point may represent a difference with respect to those of the Dirac theory [20]. In addition, the monopole Dirac charge is quantized in contrast to the effective magnetic charge of the spin-ice strings which can have any value.…”

Section: Introductionmentioning

confidence: 67%

Molecular Em Fields and Dynamical Responses in Solids With Magnetic Charges

Costa‐Quintana¹,

López‐Aguilar²

2011

PIER

View full text Add to dashboard Cite

Abstract-The monopoles are theoretically defined as charges which produce fields whose divergence is, obviously, different from zero. However, the entities which have been experimentally detected in the spin-ices, with mimetic behavior to that of the magnetic monopoles, generate magneti c fields which seem to be compatible with ∇ · B = 0. This apparent contradiction can create confusion and therefore it requires explanation. In this paper we have carried out an analysis of the different electromagnetic fields in the spinices materials. We clarify the differences between the average fields of standard Maxwell equations with zero divergence even in spin-ices and the non macroscopic fields when there are magnetic monopoles in these materials. We give the molecular or local fields which allow us to determine the molecular polarizability. We combine the extended Clausius-Mossotti equations with the Lorentz-Drude model for obtaining the extended susceptibility and the optical conductivity which can be used for explaining the action of the electromagnetic fields in spin-ices.

show abstract

Large Area Artificial Spin Ice and Anti‐Spin Ice Ni₈₀Fe₂₀ Structures: Static and Dynamic Behavior

Zhou

Chua

Singh

et al. 2016

Adv Funct Materials

View full text Add to dashboard Cite

Artificial spin ice has been the subject of extensive investigation in the last few years due to advances in nanotechnology and characterization techniques. So far, most of the studies have been limited to local probe of small area magnetic elements due to limitations with lithographic techniques used. In this study, large area spin ice and anti‐spin ice Ni80Fe20 structures with three lattice configurations have been fabricated using deep ultraviolet lithography at 193 nm exposure wavelength. The static and dynamic properties are systematically characterized using vibrating sample magnetometer, magnetic force microscopy, and broadband ferromagnetic resonance spectroscopy. Intriguing static and dynamic behaviors are observed due to the geometrical arrangement of the nanomagnets in the lattice. When the nanomagnets are saturated at high field, multiple resonance peaks whose frequencies are strongly dependent on the orientation of the applied magnetic field are observed. The experimental results are in qualitative agreement with the micromagnetic simulations. These findings may find application in the design of magnetically controlled tunable microwave filters.

show abstract

Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice

Cited by 404 publications

References 39 publications

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

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

Molecular Em Fields and Dynamical Responses in Solids With Magnetic Charges

Large Area Artificial Spin Ice and Anti‐Spin Ice Ni₈₀Fe₂₀ Structures: Static and Dynamic Behavior

Contact Info

Product

Resources

About

Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice

Cited by 404 publications

References 39 publications

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

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

Molecular Em Fields and Dynamical Responses in Solids With Magnetic Charges

Large Area Artificial Spin Ice and Anti‐Spin Ice Ni80Fe20 Structures: Static and Dynamic Behavior

Contact Info

Product

Resources

About

Large Area Artificial Spin Ice and Anti‐Spin Ice Ni₈₀Fe₂₀ Structures: Static and Dynamic Behavior