Ultra-high vacuum compatible preparation chain for intermetallic compounds

Bauer, Andreas; Benka, Georg; Regnat, Alexander; Pfleiderer, C.

doi:10.1063/1.4967011

Cited by 23 publications

(20 citation statements)

References 51 publications

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“…A large single crystal of Fe 1- x Co x Si with x = 0.5 was grown by means of the optical floating zone technique under ultrahigh vacuum conditions ( 26 , 39 , 40 ). From the single-crystal ingot, we cut a bulk sample of 200 μm thickness along a 〈100〉 axis using x-ray Laue diffraction and a wire saw.…”

Section: Methodsmentioning

confidence: 99%

Entropy-limited topological protection of skyrmions

et al. 2017

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Section: Methodsmentioning

confidence: 99%

Entropy-limited topological protection of skyrmions

et al. 2017

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“…For our study high-quality single-crystal samples of MnSi were grown by means of optical float-zoning under ultra-high vacuum compatible conditions [67,68]. The AC susceptibility and specific heat was measured on a cubic sample with an edge length of 2 mm and surfaces perpendicular to 100 and 110 .…”

Section: Experimental Methodsmentioning

confidence: 99%

Weak Crystallization of Fluctuating Skyrmion Textures in MnSi

et al. 2019

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We report an experimental study of the emergence of non-trivial topological winding and longrange order across the paramagnetic to skyrmion lattice transition in the transition metal helimagnet MnSi. Combining measurements of the susceptibility with small angle neutron scattering, neutron resonance spin echo spectroscopy and all-electrical microwave spectroscopy, we find evidence of skyrmion textures in the paramagnetic state exceeding 10 3Å with lifetimes above several 10 −9 s. Our experimental findings establish that the paramagnetic to skyrmion lattice transition in MnSi is well-described by the Landau soft-mode mechanism of weak crystallization, originally proposed in the context of the liquid to crystal transition. As a key aspect of this theoretical model, the modulation-vectors of periodic small amplitude components of the magnetization form triangles that add to zero. In excellent agreement with our experimental findings, these triangles of the modulation-vectors entail the presence of the non-trivial topological winding of skyrmions already in the paramagnetic state of MnSi when approaching the skyrmion lattice transition. I. MOTIVATIONA pre-requisite for the definition of topological magnetic textures is the presence of a continuous magnetization field with a finite amplitude in space and time. An example par excellence of such textures are magnetic skyrmions, representing topologically nontrivial whirls of this magnetization field [1]. The notions of topological winding and topological stability of such skyrmions are only meaningful when the magnetization is sufficiently smooth on local scales. This condition may be readily satisfied in systems exhibiting long-range magnetic order for temperatures far below the transition temperature T c . In contrast, changes of the topological properties require that the magnetization is capable of vanishing on short length and time scales. The associated microscopic mechanisms underlying the transition of skyrmions into different types of conventional long-range magnetic order have been explored in a large number of theoretical and experimental studies [2][3][4][5][6][7][8].A major unresolved question concerns, in contrast, the formation of skyrmion lattice order when starting from a state that is essentially paramagnetic and dominated by an abundance of fluctuations such that the local magnetization, on a coarse-grained level, practically vanishes on average [9][10][11][12][13][14][15]. This alludes to the question whether topologically non-trivial characteristics exist already in * a paramagnetic state, and how they may be accounted for in the framework of the present-day classification of phase transitions [16][17][18]. It connects also with the relevance of non-trivial topological properties in the search for novel electronic properties of solids, e.g., at quantum phase transitions [19,20].Magnetic skyrmions are ideally suited to address this question. However, they are typically portrayed from either one of two seemingly contrary points of view. On the one hand...

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“…In our study we investigated large single crystals of MnSi, Mn 1−x Fe x Si with x Fe = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.16, 0.19, 0.22, and Mn 1−x Co x Si with x Co = 0.02, 0.04 grown by means of the optical floating-zone technique under ultra-high vacuum compatible conditions [102][103][104]. The growth process and the metallurgical characterization used for all samples followed the procedure described in Ref.…”

Section: A Sample Preparationmentioning

confidence: 99%

Evolution of magnetocrystalline anisotropies in Mn1−xFexSi and Mn1−x
Kindervater
¹
,
Adams
²
,
Bauer
³

et al. 2020
Phys. Rev. B
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We report a comprehensive small-angle neutron scattering (SANS) study of magnetic correlations in Mn 1−x Fe x Si at zero magnetic field. To delineate changes of magnetocrystalline anisotropies (MCAs) from effects due to defects and disorder, we recorded complementary susceptibility and high-resolution specific heat data and investigated selected compositions of Mn 1−x Co x Si. For all systems studied, the helimagnetic transition temperature and magnetic phase diagrams evolve monotonically with composition consistent with literature. The SANS intensity patterns of the spontaneous magnetic order recorded under zero-field cooling, which were systematically tracked over forty angular positions, display strong changes of the directions of the intensity maxima and smeared out intensity distributions as a function of composition. We show that cubic MCAs account for the complex evolution of the SANS patterns, where for increasing x the character of the MCAs shifts from terms that are fourth order to terms that are sixth order in spin-orbit coupling. The magnetic field dependence of the susceptibility and SANS establishes that the helix reorientation as a function of magnetic field for Fe-or Co-doped MnSi is dominated by pinning due to defects and disorder. The presence of well-defined thermodynamic anomalies of the specific heat at the phase boundaries of the skyrmion lattice phase in the doped samples and properties observed in Mn 1−x Co x Si establishes that the pinning due to defects and disorder remains, however, weak and comparable to the field scale of the helix reorientation. The observation that MCAs, which are sixth order in spin-orbit coupling, play an important role for the spontaneous order in Mn 1−x Fe x Si and Mn 1−x Co x Si offers a fresh perspective for a wide range of topics in cubic chiral magnets such as the generic magnetic phase diagram, the morphology of topological spin textures, the paramagnetic-to-helical transition, and quantum phase transitions.

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Ultra-high vacuum compatible preparation chain for intermetallic compounds

Cited by 23 publications

References 51 publications

Entropy-limited topological protection of skyrmions

Entropy-limited topological protection of skyrmions

Weak Crystallization of Fluctuating Skyrmion Textures in MnSi

Evolution of magnetocrystalline anisotropies in Mn1−xFexSi and Mn1−x
Kindervater
¹
,
Adams
²
,
Bauer
³

et al. 2020
Phys. Rev. B
Self Cite
22
4
17
0
View full text Add to dashboard Cite

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Ultra-high vacuum compatible preparation chain for intermetallic compounds

Cited by 23 publications

References 51 publications

Entropy-limited topological protection of skyrmions

Entropy-limited topological protection of skyrmions

Weak Crystallization of Fluctuating Skyrmion Textures in MnSi

Evolution of magnetocrystalline anisotropies in Mn1−xFexSi and Mn1−xKindervater1, Adams2, Bauer3 et al. 2020Phys. Rev. BSelf Cite224170View full textAdd to dashboardCite

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Evolution of magnetocrystalline anisotropies in Mn1−xFexSi and Mn1−x
Kindervater
¹
,
Adams
²
,
Bauer
³

et al. 2020
Phys. Rev. B
Self Cite
22
4
17
0
View full text Add to dashboard Cite