Spin dynamics and spin freezing at ferromagnetic quantum phase transitions

Schmakat, Philipp; Wagner, M.; Ritz, Robert A.; Bauer, Andreas; Brando, M.; Deppe, M.; Duncan, W. J.; Duvinage, C.; Geibel, C.; Grosche, F. M.; Hirschberger, Max; Hradil, K.; Meven, Martin; Neubauer, Andreas; Schulz, Michael; Senyshyn, Anatoliy; Süllow, S.; Pedersen, B.; Böni, P.; Pfleiderer, C.

doi:10.1140/epjst/e2015-02445-4

Cited by 12 publications

(8 citation statements)

References 88 publications

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“…Concerning the effects of thermal fluctuations, we note that a remarkably complete theoretical and experimental understanding of spin waves in cubic chiral magnets has been developed, including Cu2OSeO3 (30,31,34,35,(52)(53)(54). This includes the effects of critical fluctuations within a Brazovskii scenario of a fluctuation-induced first order transition and the stabilization of the skyrmion phase by virtue of thermal Gaussian fluctuations (55,56).…”

Section: Discussionmentioning

confidence: 99%

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Zhang

Laan

Müller

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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It is commonly assumed that surfaces modify the properties of stable materials within the top few atomic layers of a bulk specimen only. Exploiting the polarization dependence of resonant elastic X-ray scattering to go beyond conventional diffraction and imaging techniques, we have determined the depth dependence of the full 3D spin structure of skyrmions-that is, topologically nontrivial whirls of the magnetization-below the surface of a bulk sample of CuOSeO We found that the skyrmions change exponentially from pure Néel- to pure Bloch-twisting over a distance of several hundred nanometers between the surface and the bulk, respectively. Though qualitatively consistent with theory, the strength of the Néel-twisting at the surface and the length scale of the variation observed experimentally exceed material-specific modeling substantially. In view of the exceptionally complete quantitative theoretical account of the magnetic rigidities and associated static and dynamic properties of skyrmions in CuOSeO and related materials, we conclude that subtle changes of the materials properties must exist at distances up to several hundred atomic layers into the bulk, which originate in the presence of the surface. This has far-reaching implications for the creation of skyrmions in surface-dominated systems and identifies, more generally, surface-induced gradual variations deep within a bulk material and their impact on tailored functionalities as an unchartered scientific territory.

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Section: Discussionmentioning

confidence: 99%

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Zhang

Laan

Müller

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…Motivated by the sensitivity to pressure, selected cubic chiral magnets have been among the first materials in which QPTs were studied under controlled conditions using hydrostatic pressure [8,9,58]. Based on the excellent account of their magnetic properties at ambient pressure as compared with other strongly correlated materials, these studies have become an important point of reference for the general understanding of QPTs in d-and f -electron materials [10,59].…”

Section: Quantum Phase Transitions Under Pressurementioning

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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4
17
0
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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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“…The maximum achievable neutron flux amounts to 1 Â 10 8 cm À2 s À1 at L/D = 400. The ANTARES instrument can be routinely used for neutron radiography and tomography, Bragg edge imaging (Woracek et al, 2014), and neutron depolarization imaging (Schmakat et al, 2015). Furthermore, as the beamline is compatible with the whole sample environment available at FRM II, complex experiments involving non-ambient conditions (such as high magnetic fields, low or high temperatures) can be performed.…”

Section: The Antares Beamlinementioning

confidence: 99%

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

et al. 2016

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neutron radiography; neutron imaging; neutron grating interferometry; neutron dark-field imaging; small-angle neutron scattering; ultra-small-angle neutron scattering AbstractNeutron grating interferometry is an advanced method in neutron imaging that allows the simultaneous recording of the transmission, the differential phase and the darkfield image. Especially the latter has recently received high interest because of its unique contrast mechanism which marks ultra-small-angle neutron scattering within the sample. Hence, in neutron grating interferometry, an imaging contrast is generated by scattering of neutrons off micrometer-sized inhomogeneities. Although the scatterer cannot be resolved it leads to a measurable local decoherence of the beam. Here, a arXiv:1602.08846v1 [cond-mat.mtrl-sci] 29 Feb 2016 2 report is given on the design considerations, principles and applications of a new neutron grating interferometer which has recently been implemented at the ANTARES beamline at the Heinz Maier-Leibnitz Zentrum. Its highly flexible design allows to perform experiments such as directional and quantitative dark-field imaging which provide spatially resolved information on the anisotropy and shape of the microstructure of the sample. A comprehensive overview of the nGI principle is given, followed by theoretical considerations to optimize the setup performance for different applications.Furthermore, an extensive characterization of the setup is presented and its abilities are demonstrated on selected case studies: (i) dark-field imaging for material differentiation, (ii) directional dark-field imaging to mark and quantify micrometer anisotropies within the sample and (iii) quantitative dark-field imaging, providing additional size information on the sample's microstructure by probing its autocorrelation function.

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Spin dynamics and spin freezing at ferromagnetic quantum phase transitions

Cited by 12 publications

References 88 publications

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

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

et al. 2020
Phys. Rev. B
Self Cite
23
4
17
0
View full text Add to dashboard Cite

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

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Spin dynamics and spin freezing at ferromagnetic quantum phase transitions

Cited by 12 publications

References 88 publications

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Reciprocal space tomography of 3D skyrmion lattice order in a chiral magnet

Evolution of magnetocrystalline anisotropies in Mn1−xFexSi and Mn1−xKindervater1, Adams2, Bauer3 et al. 2020Phys. Rev. BSelf Cite234170View full textAdd to dashboardCite

The new neutron grating interferometer at the ANTARES beamline: design, principles and applications

Contact Info

Product

Resources

About

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

et al. 2020
Phys. Rev. B
Self Cite
23
4
17
0
View full text Add to dashboard Cite