Thermal generation, manipulation and thermoelectric detection of skyrmions

Wang, Zidong; Guo, Minghua; Zhou, Hengan; Le, Zhao; Xu, Teng; Tomasello, Riccardo; Bai, Haitao; Dong, Zhe; Je, Soong-Geun; Chao, Weilun; Han, Hee‐Sung; Lee, Sooseok; Lee, Ki-Suk; Yao, Yuan; Han, Wei; Song, Cheng; Wu, Huaqiang; Carpentieri, Mario; Finocchio, G.; Im, Mi‐Young; Lin, Shi-Zeng; Jiang, Wanjun

doi:10.1038/s41928-020-00489-2

Cited by 107 publications

(77 citation statements)

References 50 publications

(142 reference statements)

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“…In some materials and for certain applications such as a skyrmion‐based racetrack memory device [ 15 ] that relies on deterministic dynamics, [ 20 ] thermal noise can be a severe problem that can even be a dominant effect determining the skyrmion nucleation, stability, and addressability. [ 21–23 ] In contrast, nondeterministic thermal dynamics has actually been exploited recently for alternative types of devices that aim at nonconventional logic, such as reservoir computing, [ 24 ] and in particular skyrmion‐based probabilistic computing [ 25 ] and token‐based Brownian computing. [ 26 ]…”

Section: Introductionmentioning

confidence: 99%

Commensurability between Element Symmetry and the Number of Skyrmions Governing Skyrmion Diffusion in Confined Geometries

Song

Kerber

Rothörl

et al. 2021

Adv Funct Materials

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Magnetic skyrmions are topological magnetic structures, which exhibit quasi‐particle properties and can show enhanced stability against perturbation from thermal noise. Recently, thermal Brownian diffusion of these quasi‐particles has been found in continuous films, and unconventional computing applications have received significant attention, requiring structured elements. Thus, as the next necessary step, skyrmion diffusion in confined geometries is studied, and it is found to be qualitatively different: The diffusion is governed by the interplay between the total number of skyrmions and the structure geometry. In particular, the effect of circular and triangular geometrical confinement is ascertained. It is found that for triangular geometries, the behavior is drastically different for the cases when the number of skyrmions in the element is either commensurate or incommensurate with a symmetric filling of the element. This influence of commensurability is corroborated by simulations of a quasi‐particle model.

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Section: Introductionmentioning

confidence: 99%

Commensurability between Element Symmetry and the Number of Skyrmions Governing Skyrmion Diffusion in Confined Geometries

Song

Kerber

Rothörl

et al. 2021

Adv Funct Materials

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“…Thermal activation has usually been considered detrimental to magnetic skyrmions due to its potential to bypass their topological protection, thus being able to irreversibly deform or switch the chiral structures. Previous results have shown that skyrmions can be created by Joule heating and temperature gradients present in the device [17,19], but there is little published information on the behavior of magnetic skyrmions under strong thermal effects. The study of thermal effects in skyrmions can provide guidelines for room-temperature skyrmion-based devices [20][21][22][23] and give further insight on the generation mechanisms of skyrmions via temperature pulses that have been observed both by calculations and experiments [19,24,25].…”

Section: Introductionmentioning

confidence: 99%

“…Previous results have shown that skyrmions can be created by Joule heating and temperature gradients present in the device [17,19], but there is little published information on the behavior of magnetic skyrmions under strong thermal effects. The study of thermal effects in skyrmions can provide guidelines for room-temperature skyrmion-based devices [20][21][22][23] and give further insight on the generation mechanisms of skyrmions via temperature pulses that have been observed both by calculations and experiments [19,24,25]. Furthermore, the thermally induced skyrmion creation/annihilation and skyrmion dynamics show their potential as true random seed generators and provide insight on skyrmion transport under elevated temperature conditions [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Spontaneous creation and annihilation dynamics of magnetic skyrmions at elevated temperature

et al. 2021

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Skyrmions are topologically protected nanoscale magnetic structures with a wide range of potential applications. Here we determine the life cycle of skyrmions from their creation to their intrinsic dynamics and thermal stability to their eventual thermodynamic demise. Using atomistic simulations of Ir/Co/Pt, parameterized from ab initio calculations, we demonstrate the thermal phase transition to a skyrmion state under application of a perpendicular magnetic field. The created skyrmions exhibit Brownian particlelike dynamics driven by the underlying thermal spin fluctuations. At an elevated temperature window well below the Curie temperature, the skyrmions are metastable and can collapse to a uniform magnetic state. With application of an external magnetic field, the intrinsic local thermal spin fluctuations at this elevated temperature window are sufficiently large to allow the spontaneous formation of new skyrmions in thermodynamic equilibrium analogous to a spontaneous skyrmion gas. Such a system could be used to implement a skyrmion-based true random number generator.

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“…The electric current then exerts a force on the skyrmions via spin-transfer torque or spin-orbit torque, resulting in a complicated interaction between spin textures and heat current. These complex thermal effects have been demonstrated by recent work on the temperature gradient-driven skyrmion diffusion in a metallic multi-layer film 14 .…”

Section: Introductionmentioning

confidence: 88%

Real-space observations of 60-nm skyrmion dynamics in an insulating magnet under low heat flow

Kagawa

Seki

et al. 2021

Nat Commun

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Thermal-current induced electron and spin dynamics in solids –dubbed “caloritronics”– have generated widespread interest in both fundamental physics and spintronics applications. Here, we examine the dynamics of nanometric topological spin textures, skyrmions driven by a temperature gradient ∇T or heat flow, that are evaluated through in-situ real-space observations in an insulating helimagnet Cu2OSeO3. We observe increases of the skyrmion velocity and the Hall angle with increasing ∇T above a critical value of ~ 13 mK/mm, which is two orders of magnitude lower than the ∇T required to drive ferromagnetic domain walls. A comparable magnitude of ∇T is also observed to move the domain walls between a skyrmion domain and the non-topological conical-spin domain from cold to hot regions. Our results demonstrate the efficient manipulation of skyrmions by temperature gradients, a promising step towards energy-efficient “green” spintronics.

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Thermal generation, manipulation and thermoelectric detection of skyrmions

Cited by 107 publications

References 50 publications

Commensurability between Element Symmetry and the Number of Skyrmions Governing Skyrmion Diffusion in Confined Geometries

Commensurability between Element Symmetry and the Number of Skyrmions Governing Skyrmion Diffusion in Confined Geometries

Spontaneous creation and annihilation dynamics of magnetic skyrmions at elevated temperature

Real-space observations of 60-nm skyrmion dynamics in an insulating magnet under low heat flow

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