Energy Minimization and ac Demagnetization in a Nanomagnet Array

Ke, Xianglin; Li, J.; Nisoli, Cristiano; Lammert, Paul E.; McConville, W.; Wang, R. F.; Crespi, Vincent H.; Schiffer, P.

doi:10.1103/physrevlett.101.037205

Cited by 127 publications

(136 citation statements)

References 26 publications

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“…In fact, the anisotropy barrier preventing the macrospin associated with a dot from flipping is much larger than room temperature, so dynamics can only be induced by applying a magnetic field H = hθ. We can expect that a small h does not affect the configuration, while a large h dominates dipolar interactions and spins simply follow the field [9]. Interesting collective effects arise when |h − h c | ∼ g, where h c is the minimum field required to flip an isolated spin and g is of the order of the dipolar interactions.…”

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confidence: 99%

Vertex Dynamics in Finite Two-Dimensional Square Spin Ices

2010

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Local magnetic ordering in artificial spin ices is discussed from the point of view of how geometrical frustration controls dynamics and the approach to steady state. We discuss the possibility of using a particle picture based on vertex configurations to interpret time evolution of magnetic configurations. Analysis of possible vertex processes allows us to anticipate different behaviors for open and closed edges and the existence of different field regimes. Numerical simulations confirm these results and also demonstrate the importance of correlations and long range interactions in understanding particle population evolution. We also show that a mean field model of vertex dynamics gives important insights into finite size effects. Introduction.-Spin ices are geometrically frustrated magnetic systems, where interaction energies are minimized by local arrangements of spins resembling the ice rule for the ground state of solid water, i.e., two-in, twoout spin configurations [1,2]. Spin ices display several interesting features including zero point entropy [3], spin freezing, and hysteresis [4]. The role of long range interactions in three dimensional spin ices is also interesting, as the long range dipolar interactions between spins lead to a state that can be described using the short range ice rules [5].

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confidence: 99%

Vertex Dynamics in Finite Two-Dimensional Square Spin Ices

2010

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“…The reliable and repeatable acquisition of square ice ground state (GS) order has been a desirable goal [66,93]. Despite theoretical predictions [47], however, a complete GS has not been achieved in nanomagnetic ice systems; instead, only short-range-ordered GS can be reached experimentally by rotating-field demagnetization protocols [43,70].…”

Section: Ice Ground State Of Square Skyrmion Icementioning

confidence: 99%

“…Artificial nanomagnet spin ice systems have been realized experimentally for square [43,50,51,56,66], and honeycomb [49,52,68] lattices, each having different analogous features to the naturally occurring rare-earth pyrochlore lattice [37]. In these ice systems, each nanomagnet plays the role of an effective macrospin, and the spin direction is defined to point in the direction of the magnetic moment.…”

Section: Introductionmentioning

confidence: 99%

“…The most studied artificial spin ice systems are created using arrays of nanomagnets with a bistable single-domain magnetization [43,44,[46][47][48][49][50][51][52][53][54][55][56][57][63][64][65][66][67]. Artificial nanomagnet spin ice systems have been realized experimentally for square [43,50,51,56,66], and honeycomb [49,52,68] lattices, each having different analogous features to the naturally occurring rare-earth pyrochlore lattice [37].…”

Section: Introductionmentioning

confidence: 99%

“…The vertex state of the system can be directly imaged by locally probing the magnetic moment of a single constituent nanomagnet via magnetic microscopy, such as with magnetic force microscopy [53], LTEM [69], or photoemission electron microscopy [68]. In square nanomagnet ices [43,50,51,56,66], however, the ice-rule-obeying states with "two-spins-in/two-spins-out"…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Emergent geometric frustration of artificial magnetic skyrmion crystals

Reichhardt

Gan

et al. 2016

Phys. Rev. B

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Magnetic skyrmions have been receiving growing attention as potential information storage and magnetic logic devices since an increasing number of materials have been identified that support skyrmion phases. Explorations of artificial frustrated systems have led to new insights into controlling and engineering new emergent frustration phenomena in frustrated and disordered systems. Here, we propose a skyrmion spin ice, giving a unifying framework for the study of geometric frustration of skyrmion crystals in a non-frustrated artificial geometrical lattice as a consequence of the structural confinement of skyrmions in magnetic potential wells. The emergent ice rules from the geometrically frustrated skyrmion crystals highlight a novel phenomenon in this skyrmion system: emergent geometrical frustration. We demonstrate how skyrmion crystal topology transitions between a non-frustrated periodic configuration and a frustrated ice-like ordering can also be realized reversibly. The proposed artificial frustrated skyrmion systems can be annealed into different ice phases with an applied current induced spin-transfer torque, including a long range ordered ice rule obeying ground state, as-relaxed random state, biased state and monopole state. The spin-torque reconfigurability of the artificial skyrmion ice states, difficult to achieve in other artificial spin ice systems, is compatible with standard spintronic device fabrication technology, which makes the semiconductor industrial integration straightforward.

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Field‐Induced Antiferromagnetic Correlations in a Nanopatterned Van der Waals Ferromagnet: A Potential Artificial Spin Ice

Noah,

Fridman,

Zur

et al. 2024

Advanced Science

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Nano‐patterned magnetic materials have opened new venues for the investigation of strongly correlated phenomena including artificial spin‐ice systems, geometric frustration, and magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin 2D van der Waals (vdW) magnets, a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter can be assessed. Here, it is shown that square islands of CrGeTe3 vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin‐ice. By using a combination of SQUID‐on‐tip microscopy, focused ion beam lithography, and atomistic spin dynamic simulations, it is shown that a square array of CGT island as small as 150 × 150 × 60 nm3 have tunable dipole–dipole interactions, which can be precisely controlled by their lateral spacing. There is a crossover between non‐interacting islands and significant inter‐island anticorrelation depending on how they are spatially distributed allowing the creation of complex magnetic patterns not observable at the isolated flakes. These findings suggest that the cross‐talk between the nano‐patterned magnets can be explored in the generation of even more complex spin configurations where exotic interactions may be manipulated in an unprecedented way.

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Energy Minimization and ac Demagnetization in a Nanomagnet Array

Cited by 127 publications

References 26 publications

Vertex Dynamics in Finite Two-Dimensional Square Spin Ices

Vertex Dynamics in Finite Two-Dimensional Square Spin Ices

Emergent geometric frustration of artificial magnetic skyrmion crystals

Field‐Induced Antiferromagnetic Correlations in a Nanopatterned Van der Waals Ferromagnet: A Potential Artificial Spin Ice

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