Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures

Husain, Sajid; Sisodia, Naveen; Chaurasiya, Avinash Kumar; Kumar, Ankit; Singh, Jitendra Pal; Yadav, B. S.; Akansel, Serkan; Chae, Keun Hwa; Barman, Anjan; Muduli, P. K.; Svedlindh, Peter; Chaudhary, Sujeet

doi:10.1038/s41598-018-35832-3

Cited by 25 publications

(15 citation statements)

References 88 publications

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“…The DMI of various ferromagnetic systems has been reposted to be an order of 0.1‐3 mJ/m 2 . [ 39,42–46 ] Thus, the ratio of DMI and exchange energies when T = 140 K is ≈0.1, which is an important parameter to form such helical ordering as discussed in the sections 5 and 8 of Supporting Information. This ratio implies that DMI contribution to the total energy in the Fe 5− x GeTe 2 crystal is large enough to have such helical magnetic structure as confirmed with our analytical study.…”

Section: Resultsmentioning

confidence: 99%

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Park

Kim

et al. 2021

Adv Funct Materials

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Microscopic structures and magnetic properties are investigated for Fe5−xGeTe2 single crystal, recently discovered as a promising van der Waals (vdW) ferromagnet. An Fe atom (Fe(1)) located in the outermost Fe5Ge sublayer has two possible split‐sites which are either above or below the Ge atom. Scanning tunneling microscopy shows √3 × √3 superstructures which are attributed to the ordering of Fe(1) layer. The √3 × √3 superstructures have two different phases due to the symmetry of Fe(1) ordering. Intriguingly, the observed √3 × √3 ordering breaks the inversion symmetry of crystal, resulting in substantial antisymmetric exchange interaction. The temperature dependence of magnetization reveals a sharp magnetic anomaly suggesting helical magnetism of the Fe5−xGeTe2 due to its non‐centrosymmetricity. Analytical study also supports that the observed ordering can give rise to the helimagnetism. The work will provide essential information to understand the complex magnetic properties and the origin of the new vdW ferromagnet, Fe5−xGeTe2 for future topology‐based spin devices.

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Section: Resultsmentioning

confidence: 99%

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Park

Kim

et al. 2021

Adv Funct Materials

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“…In this regard, CoFeB [69] or Heusler alloys [212,213] are perhaps better choices than Co films. Indeed, very recently, the stabilization of magnetic skyrmions in Ta/Co 2 FeAl/MgO hetero-structures with approximately 100 nm diameter is reported [214]. However, an efficient electric control of skyrmions in this material system is yet to be shown.…”

Section: Magnetic Skyrmions In Asymmetric Multilayersmentioning

confidence: 99%

Skyrmions in magnetic multilayers

et al. 2017

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Symmetry breaking together with strong spin-orbit interaction give rise to many exciting phenomena within condensed matter physics. A recent example is the existence of chiral spin textures, which are observed in magnetic systems lacking inversion symmetry. These chiral spin textures, including domain walls and magnetic skyrmions, are both fundamentally interesting and technologically promising. For example, they can be driven very efficiently by electrical currents, and exhibit many new physical properties determined by their real-space topological characteristics. Depending on the details of the competing interactions, these spin textures exist in different parameter spaces. However, the governing mechanism underlying their physical behaviors remain essentially the same. In this review article, the fundamental topological physics underlying these chiral spin textures, the key factors for materials optimization, and current developments and future challenges will be discussed. In the end, a few promising directions that will advance the development of skyrmion based spintronics will be highlighted.This review article is organized as follows:1. Topological physics of magnetic skyrmions 1.1 Origin of spin topology 1.2 Real space topological physics 1.3 Topological distinction of bubble-like spin textures 2. Interfacial chiral magnetism 2.1 From spin spiral to chiral domain wall 2.2 Physical origin of the chiral interfacial DMI 2.3 Measurement of the interfacial DMI 2.4 Unique advantages of magnetic skyrmions in heterostructures 3. Current developments in thin-film skyrmions 3.1 Writing and deleting a single skyrmion 3.2 Blowing magnetic skyrmion bubbles 3.3 Moving skyrmions in wires 3.4 Magnetic skyrmions in asymmetric trilayers 3.5 Characteristics of topological trivial bubbles 3.6 Hall effect of topological charge -skyrmion Hall effect 3.7 High frequency dynamics of magnetic skyrmion 3.8 Artificial skyrmions stabilized by interlayer coupling in thin films 3.9 Novel spin-resolved imaging techniques 3.9.1 Lorentz transmission electron microscopy 3.9.2 Spin-polarized low energy electron microscopy 3.9.3 Photoemission electron microscopy 4. PerspectivesRecent advancements in nanotechnology resulted in concomitant progress in magnetism, with two developments being particularly influential in nanomagnetic systems: controlling magnets via electric (field/current) excitations [5][6][7][8] and the discovery of topological spin textures [9]. Electric control of magnetism is made possible by utilizing the coupling between electron spin and its orbital motion.

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“…[129] Moreover, the interfacial Dzyaloshinskii-Moriya interaction (iDMI) was investigated in CFA ultrathin films of various thicknesses and with various buffer layers by measuring spin waves with Brillouin light scattering (BLS). [130,131] And the current-induced dipolar magnetic skyrmions in Co-based Heusler alloy CFA at room temperature have been reported by Husain et al [132] and Akhtar et al [133] Although they did not observe a clear skyrmion Hall effect [134] in this system due to the pinning effects, it is still very promising to explore the efficient skyrmion motion in Heusler alloys where the stabilization of magnetic skyrmions under ambient conditions is possible.…”

Section: Hall (And Related) Effectsmentioning

confidence: 59%

“…[ 130,131 ] And the current‐induced dipolar magnetic skyrmions in Co‐based Heusler alloy CFA at room temperature have been reported by Husain et al. [ 132 ] and Akhtar et al. [ 133 ] Although they did not observe a clear skyrmion Hall effect [ 134 ] in this system due to the pinning effects, it is still very promising to explore the efficient skyrmion motion in Heusler alloys where the stabilization of magnetic skyrmions under ambient conditions is possible.…”

Section: Magnetic Thermoelectric and Transport Properties Of Co‐basementioning

confidence: 99%

Spin‐Dependent Thermoelectric Transport in Cobalt‐Based Heusler Alloys

Granville

2020

Annalen der Physik

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Sitting at the intersection of spintronics and thermoelectricity, research investigating the coupling of thermoelectric, magnetic, and electrical transport properties in materials has recently found that the ferromagnetic Heusler alloys are the ideal testbeds. These materials have attracted a lot of attention due to their useful magnetotransport properties and the possibility of tailoring these properties by modifying their composition or producing heterostructures. With the diverse range of interesting phenomena in the Heusler alloys, ferromagnetic Heusler alloys are also ideal candidates for engineering spin caloritronic devices that can take advantage of the interplay of the physics of heat flow, magnetism, and electric potential. The fundamental physical concepts important to spin-dependent thermoelectrics research are introduced and recent studies of several ferromagnetic Heusler compounds are reviewed, highlighting some exceptional latest experiments on half-metallic Co 2 TiSn and the ferromagnetic Weyl semimetal Co 2 MnGa. Furthermore, the potential to generate useful magnetothermoelectric voltages in electronic devices based on the anomalous Nernst effect is discussed.

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Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures

Cited by 25 publications

References 88 publications

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Skyrmions in magnetic multilayers

Spin‐Dependent Thermoelectric Transport in Cobalt‐Based Heusler Alloys

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Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures

Cited by 25 publications

References 88 publications

Direct Observation of Fe‐Ge Ordering in Fe5−xGeTe2 Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe5−xGeTe2 Crystals and Resultant Helimagnetism

Skyrmions in magnetic multilayers

Spin‐Dependent Thermoelectric Transport in Cobalt‐Based Heusler Alloys

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Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism

Direct Observation of Fe‐Ge Ordering in Fe₅₋_xGeTe₂ Crystals and Resultant Helimagnetism