Computing in Thermal Equilibrium With Dipole-Coupled Nanomagnets

Carlton, David; Lambson, Brian; Schöll, A.; Young, A. T.; Dhuey, Scott; Ashby, Paul D.; Tuchfeld, Eduard; Bokor, Jeffrey

doi:10.1109/tnano.2011.2152851

Cited by 14 publications

(13 citation statements)

References 18 publications

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“…A particularly exciting direction for this topic is to explore the dynamics possible in the presence of thermal fluctuations. First reports of 'thermal artificial ice' are now appearing [78,81,85], and with them the technology to make nanoscale elements with extremely well defined properties is developing, as well as ideas of how to incorporate nanoscale magnets for computing at thermal equilibrium [140]. Building on the idea of reconfigurable magnetic states, it is important to look to high frequency dynamics that may lead to new types of logic and microwave frequency devices.…”

Section: Discussionmentioning

confidence: 99%

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Artificial ferroic systems: novel functionality from structure, interactions and dynamics

Heyderman¹,

Stamps²

2013

J. Phys.: Condens. Matter

216

193

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Lithographic processing and film growth technologies are continuing to advance, so that it is now possible to create patterned ferroic materials consisting of arrays of sub-1 μm elements with high definition. Some of the most fascinating behaviour of these arrays can be realised by exploiting interactions between the individual elements to create new functionality. The properties of these artificial ferroic systems differ strikingly from those of their constituent components, with novel emergent behaviour arising from the collective dynamics of the interacting elements, which are arranged in specific designs and can be activated by applying magnetic or electric fields. We first focus on artificial spin systems consisting of arrays of dipolar-coupled nanomagnets and, in particular, review the field of artificial spin ice, which demonstrates a wide range of fascinating phenomena arising from the frustration inherent in particular arrangements of nanomagnets, including emergent magnetic monopoles, domains of ordered macrospins, and novel avalanche behaviour. We outline how demagnetisation protocols have been employed as an effective thermal anneal in an attempt to reach the ground state, comment on phenomena that arise in thermally activated systems and discuss strategies for selectively generating specific configurations using applied magnetic fields. We then move on from slow field and temperature driven dynamics to high frequency phenomena, discussing spinwave excitations in the context of magnonic crystals constructed from arrays of patterned magnetic elements. At high frequencies, these arrays are studied in terms of potential applications including magnetic logic, linear and non-linear microwave optics, and fast, efficient switching, and we consider the possibility to create tunable magnonic crystals with artificial spin ice. Finally, we discuss how functional ferroic composites can be incorporated to realise magnetoelectric effects. Specifically, we discuss artificial multiferroics (or multiferroic composites), which hold promise for new applications that involve electric field control of magnetism, or electric and magnetic field responsive devices for high frequency integrated circuit design in microwave and terahertz signal processing. We close with comments on how enhanced functionality can be realised through engineering of nanostructures with interacting ferroic components, creating opportunities for novel spin electronic devices that, for example, make use of the transport of magnetic charges, thermally activated elements, and reprogrammable nanomagnet systems.

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Section: Discussionmentioning

confidence: 99%

“…One of the key challenges here is to achieve exceptionally efficient switching of magnetic elements with minimal energy lost to heat [140][141][142][143][144]. It has been proposed in fact, that magnetic logic based on switching of magnetic elements can approach the so-called Landauer limit [145].…”

Section: Figure 14mentioning

confidence: 99%

Artificial ferroic systems: novel functionality from structure, interactions and dynamics

Heyderman¹,

Stamps²

2013

J. Phys.: Condens. Matter

216

193

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“…of the circuit. Further details on signal propagation and thermal effects in nanomagnetic logic circuits can be found in [12].…”

Section: Nanomagnetic Logicmentioning

confidence: 99%

“…Indeed, both Landauer [1] and Bennett [2] have cited nanomagnets as prototypical bistable logic elements in which energy efficiency near the fundamental limits might be observed. More recently, it has been experimentally demonstrated that binary information can propagate along a chain of dipole-coupled nanomagnets without any energetic input, instead using thermal energy to move the information via Brownian motion [12].…”

Section: Introductionmentioning

confidence: 99%

Exploring the Thermodynamic Limits of Computation in Integrated Systems: Magnetic Memory, Nanomagnetic Logic, and the Landauer Limit

2011

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Nanomagnetic memory and logic circuits are attractive integrated platforms for studying the fundamental thermodynamic limits of computation. Using the stochastic Landau-Lifshitz-Gilbert equation, we show by direct calculation that the amount of energy dissipated during nanomagnet erasure approaches Landauer's thermodynamic limit of kTln(2) with high precision when the external magnetic fields are applied slowly. In addition, we find that nanomagnet systems behave according to generalized formulations of Landauer's principle that hold for small systems and generic logic operations. In all cases, the results are independent of the anisotropy energy of the nanomagnet. Lastly, we apply our computational approach to a nanomagnet majority logic gate, where we find that dissipationless, reversible computation can be achieved when the magnetic fields are applied in the appropriate order.

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“…7,8 One potential application of configurational anisotropy is to nanomagnetic logic, in which arrays of lithographically defined nanomagnets process information via nearestneighbor dipole coupling interactions. [9][10][11] Most studies of nanomagnetic logic to date have been carried out using nanomagnets with ellipsoidal or rectangular shapes that are typically assumed to exhibit only uniaxial shape anisotropy. However, a recent simulation study predicts that nanomagnetic logic using nanomagnets with a composition of both uniaxial and biaxial anisotropies could have greatly improved speed and reliability characteristics compared with shape anisotropy only.…”

mentioning

confidence: 99%

Cascade-like signal propagation in chains of concave nanomagnets

Lambson¹,

Gu²,

Carlton³

et al. 2012

Appl. Phys. Lett.

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We lithographically control the anisotropy properties of single-domain nananomagnets for use in emerging nanomagnetic logic applications. By defining concave-shaped nanomagnets to enhance the effect of configurational anisotropy, we induce the property of dual-axis remanence needed for high-speed and reliable operation of nanomagnetic logic circuits. Magneto-optical measurements verify the anisotropy properties of isolated concave nanomagnets, and photoelectron emission microscopy measurements verify signal propagation in chains of concave nanomagnets.

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Computing in Thermal Equilibrium With Dipole-Coupled Nanomagnets

Cited by 14 publications

References 18 publications

Artificial ferroic systems: novel functionality from structure, interactions and dynamics

Artificial ferroic systems: novel functionality from structure, interactions and dynamics

Exploring the Thermodynamic Limits of Computation in Integrated Systems: Magnetic Memory, Nanomagnetic Logic, and the Landauer Limit

Cascade-like signal propagation in chains of concave nanomagnets

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