Spin textures induced by quenched disorder in a reentrant spin glass: Vortices versus “frustrated” skyrmions

Mirebeau, I.; Martín, Nicolás Bas; Deutsch, Maxime; Bannenberg, Lars J.; Pappas, C.; Chaboussant, Grégory; Cubitt, R.; Decorse, Claudia; Leonov, A. O.

doi:10.1103/physrevb.98.014420

Cited by 20 publications

(14 citation statements)

References 73 publications

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“…To summarize this point, the average canting angle ϕ C increases as the transverse spin components and magnetic disorder in the transverse plane increase. Corresponding data, extracted from our previous SANS experiment on Ni 0.81 Mn 0.19 fall within the same range and follows a very similar trend 17 . This suggests that the observed vortices are relatively independent on the sample nature (single crystalline or amorphous) and could represent an immanent feature of the large family of RSG.…”

Section: Small-angle Neutron Scattering (Sans)supporting

confidence: 69%

“…First, we note band structure calculations of dilute FeMn alloys [18][19][20] where Mn-Mn NN interactions are AFM whereas Fe-Fe and and Fe-Mn NN interactions are FM. Based on previous SANS results on a crystalline Ni 0.81 Mn 0.19 sample, as well as toy models and MC simulations 17 , we interpret σ T (Q) by assuming uncorrelated defects akin to vortices, nucleated around Mn-Mn first neighbor pairs. In the simplest picture, the spins components M T are ferromagnetically correlated and rotate over an average vortex radius r d = π/Q max to compensate the transverse magnetization inside the vortex 17 .…”

Section: Small-angle Neutron Scattering (Sans)mentioning

confidence: 84%

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Field-induced vortex-like textures as a probe of the critical line in reentrant spin glasses

Martín¹,

Bannenberg²,

Deutsch³

et al. 2021

Preprint

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We study the evolution of the low-temperature field-induced magnetic defects observed under an applied magnetic field in a series of frustrated amorphous ferromagnets (Fe1−x Mnx )75P16B3Al3 (a-FeMn). Combining small-angle neutron scattering and Monte Carlo simulations, we show that the morphology of these defects resemble that of quasi-bidimensional spin vortices. They are observed in the reentrant spin-glass (RSG) phase, up to the critical concentration x C ≈ 0.36 which separates the RSG and "true" spin glass (SG) within the low temperature part of the magnetic phase diagram of a-FeMn. These vortices systematically decrease in size with increasing magnetic field or decreasing the average exchange interaction, and they finally disappear in the SG sample (x = 0.41), being replaced by field-induced correlations over finite length scales. We argue that the study of these nanoscopic defects could be used to probe the nature of the critical line between the RSG and SG phases.

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Section: Small-angle Neutron Scattering (Sans)supporting

confidence: 69%

Section: Small-angle Neutron Scattering (Sans)mentioning

confidence: 84%

Field-induced vortex-like textures as a probe of the critical line in reentrant spin glasses

Martín¹,

Bannenberg²,

Deutsch³

et al. 2021

Preprint

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“…x 7 displaying reentrant spin-glass behavior [46] as similarly reported for a number of ferromagnets [47][48][49][50][51][52], antiferromagnets [53,54], and helimagnets [55] with chemical and magnetic disorder. The spin-glass nature was confirmed by previous frequency-dependent ac susceptibility measurements for Co 7 Zn 7 Mn 6 (T c ∼ 160 K, T g ∼ 30 K) [29,31,56].…”

Section: Introductionmentioning

confidence: 75%

Metastable skyrmion lattices governed by magnetic disorder and anisotropy in β -Mn-type chiral magnets

et al. 2020

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Magnetic skyrmions are vortexlike topological spin textures often observed in structurally chiral magnets with Dzyaloshinskii-Moriya interaction. Among them, Co-Zn-Mn alloys with a β-Mn-type chiral structure host skyrmions above room temperature. In this system, it has recently been found that skyrmions persist over a wide temperature and magnetic field region as a long-lived metastable state, and that the skyrmion lattice transforms from a triangular lattice to a square one. To obtain perspective on chiral magnetism in Co-Zn-Mn alloys and clarify how various properties related to the skyrmion vary with the composition, we performed systematic studies on Co 10 Zn 10 , Co 9 Zn 9 Mn 2 , Co 8 Zn 8 Mn 4 , and Co 7 Zn 7 Mn 6 in terms of magnetic susceptibility and small-angle neutron scattering measurements. Robust metastable skyrmions with extremely long lifetime are commonly observed in all the compounds. On the other hand, the preferred orientation of the helimagnetic propagation vector and its temperature dependence dramatically change upon varying the Mn concentration. The robustness of the metastable skyrmions in these materials is attributed to topological nature of the skyrmions as affected by structural and magnetic disorder. Magnetocrystalline anisotropy as well as magnetic disorder due to frustrated Mn spins play crucial roles in giving rise to the observed change in helical states and corresponding skyrmion lattice form.

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“…Under applied field, vortexlike defects where the transverse components rotate over finite length scales (1-10 nm) have been observed in FM-RSG systems [85][86][87], likely nucleated by the strongest AF pairs. They were recently characterized in a NiMn single crystal by combining small angle neutron scattering with MC simulations [88]. The Fe 1−x Cr x system provides an interesting opportunity to investigate such topological defects.…”

Section: Towards the Cr-rich Phase: Reentrant Spin Glasses And Cr mentioning

confidence: 99%

Magnetic and atomic short range order in Fe1−xCrx alloys

et al. 2019

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We study the magnetic short range order (MSRO) in Fe 1−x Cr x (0 x 0.15) where an inversion of atomic short range order (ASRO) occurs at x C = 0.11(1). Our combination of neutron diffuse scattering and bulk magnetization measurements offers a comprehensive description of these local orders at a microscopic level. In the dilute alloys (x < 0.04), the Cr atoms bear a large moment μ Cr = −1.0(1) μ B , antiparallel to the Fe ones (μ Fe ). They fully repel their Cr first and second neighbors, and perturb the surrounding Fe moments. With increasing x, near neighbor Cr-Cr pairs start to appear and the Cr moment magnitude decreases, while μ Fe shows a rounded maximum for x 1 = 0.06(1) < x C . Above x C , ASRO turns to local Cr segregation, thereby increasing magnetic frustration. First-principles calculations reproduce the observed moment variations but overestimate the magnitude of the Cr moment. In order to reconcile theory with experiment quantitatively, we propose that the magnetic moments start canting locally, already above x 1 . This picture actually anticipates the spin glasslike behavior of Cr-rich alloys. The whole study points out the subtle interplay of MSRO and ASRO, yielding an increasing frustration as x increases, due to competing Fe-Cr and Cr-Cr interactions and Cr clustering tendency.

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Spin textures induced by quenched disorder in a reentrant spin glass: Vortices versus “frustrated” skyrmions

Cited by 20 publications

References 73 publications

Field-induced vortex-like textures as a probe of the critical line in reentrant spin glasses

Field-induced vortex-like textures as a probe of the critical line in reentrant spin glasses

Metastable skyrmion lattices governed by magnetic disorder and anisotropy in β -Mn-type chiral magnets

Magnetic and atomic short range order in Fe1−xCrx alloys

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