Nucleation and annihilation of skyrmions in Mn2CoAl observed through the topological Hall effect

Ludbrook, B.; Dubuis, Guy; Puichaud, Anne-Hélène; Ruck, B. J.; Granville, S.

doi:10.1038/s41598-017-13211-8

Cited by 59 publications

(37 citation statements)

References 38 publications

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“…We note that all published transport results comprising similar phenomenology [17][18][19][20][21][22][23][24] could be well explained using our model introducing two coexisting ferromagnetic orders. Moreover our explanation successfully describes every electrical transport feature, including dependence on magnetic field, gate voltage, temperature and thin film parameters such as doping level and film thickness, without the need to speculate about new topological physics.…”

supporting

confidence: 76%

“…The anomalous Hall effect (AHE), despite being first reported over a hundred years ago, [1] remains of significant modern research interest as its investigation in novel magnetic materials continues to yield rich physics. Recent examples of this are the quantum anomalous Hall effect [2][3][4][5][6][7][8][9][10][11][12], which offers both potential for metrological applications [13,14] and for the academic study of axion electrodynamics [5,12,15,16], as well as reports on alleged contribution to the Hall effect [17][18][19][20][21][22][23][24] associated with skyrmion magnetic textures.…”

mentioning

confidence: 99%

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Coexistence of Surface and Bulk Ferromagnetism Mimics Skyrmion Hall Effect in a Topological Insulator

Fijalkowski¹,

Hartl²,

Winnerlein³

et al. 2020

Phys. Rev. X

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Here we report the investigation of the anomalous Hall effect in the magnetically doped topological insulator (V,Bi,Sb)2Te3. We find it contains two contributions of opposite sign. Both components are found to depend differently on carrier density, leading to a sign inversion of the total anomalous Hall effect as a function of applied gate voltage. The two contributions are found to have different magnetization reversal fields, which in combination with a temperature dependent study points towards the coexistence of two ferromagnetic orders in the system. Moreover, we find that the sign of total anomalous Hall response of the system depends on the thickness and magnetic doping density of the magnetic layer. The thickness dependence suggests that the two ferromagnetic components originate from the surface and bulk of the magnetic topological insulator film. We believe that our observations provide insight on the magnetic behavior, and thus will contribute to an eventual understanding of the origin of magnetism in this material class. In addition, our data bears a striking resemblance to anomalous Hall signals often associated with skyrmion contributions. Our analysis provides a straightforward explanation for both the magnetic field dependence of the Hall signal and the observed change in sign without needing to invoke skyrmions, and thus suggest that caution is needed when making claims of effects from skyrmion phases. arXiv:1912.02766v1 [cond-mat.mes-hall]

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supporting

confidence: 76%

mentioning

confidence: 99%

Coexistence of Surface and Bulk Ferromagnetism Mimics Skyrmion Hall Effect in a Topological Insulator

Fijalkowski¹,

Hartl²,

Winnerlein³

et al. 2020

Phys. Rev. X

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“…The third category covers magnetization from the hard axis, including Cr5Te8 [19] , Fe3GeTe2 [20] , and (Cr0.9B0.1)Te. Many Mn-based Heusler compounds [21][22][23][24][25]35] have combined materials from all three categories. The topological Hall effects for the second and third categories are larger, with a large magnetic field, depending on the exchange coupling strength or magnetocrystalline anisotropy.…”

mentioning

confidence: 99%

Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Kroder

Gayles

et al. 2020

Applied Physics Letters

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The Berry phase understanding of electronic properties has attracted special interest in condensed matter physics, leading to phenomena such as the anomalous Hall effect and the topological Hall effect. A non-vanishing Berry phase, induced in momentum space by the band structure or in real space by a non-coplanar spin structure, is the origin of both effects. Here, we report a sign conversion of the anomalous Hall effect and a large topological Hall effect in (Cr0.9B0.1)Te single crystals. The spin reorientation from an easy-axis structure at high temperature to an easy-cone structure below 140 K leads to conversion of the Berry curvature, which influences both, anomalous and topological, Hall effects in the presence of an applied magnetic field and current. We compare and summarize the topological Hall effect in four categories with different mechanisms and have a discussion into the possible artificial fake effect of topological Hall effect in polycrystalline samples, which provides a deep understanding of the relation between spin structure and Hall properties.In condensed matter physics, Berry phases have enabled a wider understanding of many physical concepts and phenomena, such as chiral anomalies [1,2] , magnetic monopoles [3] , and the anomalous Nernst effect [4] . Among them, the intrinsic anomalous Hall effect (AHE) requires the absence of time reversal symmetry and the orbital degeneracy to be lifted. The former is usually seen in ferromagnetic systems but also can be found in specific antiferromagnetic systems. The latter is due to relativistic effects such as the spin-orbit interaction, but can also be induced by a non-collinear magnetic spin texture [5,6] . The combination of these phenomena leads to momentumspace Berry curvature as a linear response to an applied electric field [7,8] . However, a real-space Berry phase originating from non-coplanar spin texture or magnetic topological excitations like

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Section: Magnetic Thermoelectric and Transport Properties Of Co‐basementioning

confidence: 81%

“…For example, the skyrmion phase was recently detected through the THE at low temperature range in Heusler alloys Mn 2 RhSn, [126] Mn 1.4 (Pt,Pd)Sn, [127,128] and Mn 2 CoAl. [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: 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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Nucleation and annihilation of skyrmions in Mn2CoAl observed through the topological Hall effect

Cited by 59 publications

References 38 publications

Coexistence of Surface and Bulk Ferromagnetism Mimics Skyrmion Hall Effect in a Topological Insulator

Coexistence of Surface and Bulk Ferromagnetism Mimics Skyrmion Hall Effect in a Topological Insulator

Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Spin‐Dependent Thermoelectric Transport in Cobalt‐Based Heusler Alloys

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