Flip of spin helix chirality and ferromagnetic state in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Fe</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Co</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi>Ge</mml:mi></mml:mrow></mml:math>compounds

Grigoriev, S. V.; Siegfried, S.-A.; Altynbayev, E. V.; Potapova, N. M.; Dyadkin, Vadim; Moskvin, E. V.; Menzel, D.; Heinemann, A.; Axenov, S. N.; Фомичева, Л.Н.; Tsvyashchenko, A. V.

doi:10.1103/physrevb.90.174414

Cited by 41 publications

(54 citation statements)

References 16 publications

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“…15(b). In these results we find the zero crossing of the DMI to be at y ∼ 0.45, slightly lower than zero crossing of y = 0.6 found in bulk crystals [37]. Our experimental zero-crossing composition is reproduced by our DFT calculations, which is also at a slightly lower value than that calculated by the spin current method [28,79].…”

Section: A Helical Magnetismsupporting

confidence: 43%

“…The wavelengths are the largest for intermediate values of y in the region that the helix wave vector was found to go to zero in Ref. [37].…”

Section: A Helical Magnetismmentioning

confidence: 82%

“…In addition to Mn 1−x Fe x Ge, substituting Co into FeGe shows that the helix pitch also changes magnitude as a function of y in polycrystalline samples of Fe 1−y Co y Ge [37]. However, CoGe with the same crystal symmetry displays paramagnetism in the ground state, with no net magnetization to observe AHE, THE, or any phenomena induced by DMI.…”

Section: Introductionmentioning

confidence: 98%

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Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−yCoyGe films

et al. 2018

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Epitaxial films of the B20-structure compound Fe 1−y Co y Ge were grown by molecular beam epitaxy on Si (111) substrates. The magnetization varied smoothly from the bulklike values of one Bohr magneton per Fe atom for FeGe to zero for nonmagnetic CoGe. The chiral lattice structure leads to a Dzyaloshinskii-Moriya interaction (DMI), and the films' helical magnetic ground state was confirmed using polarized neutron reflectometry measurements. The pitch of the spin helix, measured by this method, varies with Co content y and diverges at y ∼ 0.45. This indicates a zero crossing of the DMI, which we reproduced in calculations using first-principles methods. We also measured the longitudinal and Hall resistivity of our films as a function of magnetic field, temperature, and Co content y. The Hall resistivity is expected to contain contributions from the ordinary, anomalous, and topological Hall effects. Both the anomalous and topological Hall resistivities show peaks around y ∼ 0.5. Our first-principles calculations show a peak in the topological Hall constant at this value of y, related to the strong spin polarization predicted for intermediate values of y. Our calculations predict half-metallicity for y = 0.6, consistent with the experimentally observed linear magnetoresistance at this composition, and potentially related to the other unusual transport properties for intermediate value of y. While it is possible to reconcile theory with experiment for the various Hall effects for FeGe, the large topological Hall resistivities for y ∼ 0.5 are much larger than expected when the very small emergent fields associated with the divergence in the DMI are taken into account.

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Section: A Helical Magnetismsupporting

confidence: 43%

“…The wavelengths are the largest for intermediate values of y in the region that the helix wave vector was found to go to zero in Ref. [37].…”

Section: A Helical Magnetismmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 98%

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Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−yCoyGe films

et al. 2018

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“…The correlation between the Skyrmion helicity and crystal chirality has been already discussed in the literature [7,8]. Recent experiments have demonstrated in addition a change of the Skyrmion helicity with the chemical composition in the case of B20 alloys [9,10] while the crystal chirality was unaltered. This finding opens an alternative possibility for DMI engineering in order to manipulate the Skyrmion helicity.…”

Section: Introductionmentioning

confidence: 79%

Composition-dependent magnetic response properties of Mn1−xFexGe alloys

et al. 2018

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The composition-dependent behavior of the Dzyaloshinskii-Moriya interaction (DMI), the spinorbit torque (SOT), as well as anomalous and spin Hall conductivities of Mn1−xFexGe alloys have been investigated by first-principles calculations using the relativistic multiple scattering KorringaKohn-Rostoker (KKR) formalism. The Dxx component of the DMI exhibits a strong dependence on the Fe concentration, changing sign at x ≈ 0.85 in line with previous theoretical calculations as well as with experimental results demonstrating the change of spin helicity at x ≈ 0.8. A corresponding behavior with a sign change at x ≈ 0.5 is predicted also for the Fermi sea contribution to the SOT, as this is closely related to the DMI. In the case of anomalous and spin Hall effects it is shown that the calculated Fermi sea contributions are rather small and the composition-dependent behavior of these effects are determined mainly by the electronic states at the Fermi level. The spin-orbitinduced scattering mechanisms responsible for both these effects suggest a common origin of the minimum of the AHE and the sign change of the SHE conductivities.

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“…A magnetic field (0.0 -0.5 T) was applied perpendicular to the incident beam. The FeGe sample with the mass of 0.1 g was the same as used in our previous work 23 . It was synthesized using the high pressure method (see 24 for details).…”

Section: Elastic Small-angle Neutron Measurementsmentioning

confidence: 99%

Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

et al. 2017

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We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225 K up to TC ≈ 278.7 K by small-angle neutron scattering. The method we have used is based on [S. V. Grigoriev et al. Phys. Rev. B 92 220415(R) (2015)] and was extended here for the application in polycrystalline samples. We confirm the validity of the anisotropic spin-wave dispersion for FeGe caused by the Dzyaloshinskii-Moriya interaction. We have shown that the spinwave stiffness A for FeGe helimagnet decreases with a temperature as A(T ) = 194(1 − 0.7(T /TC ) 4.2 ) meVÅ 2 . The finite value of the spin-wave stiffness A = 58 meVÅ 2 at TC classifies the order-disorder phase transition in FeGe as being the first order one.

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Flip of spin helix chirality and ferromagnetic state inFe1−xCoxGecompounds

Cited by 41 publications

References 16 publications

Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−yCoyGe films

Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−yCoyGe films

Composition-dependent magnetic response properties of Mn1−xFexGe alloys

Spin-wave dynamics in the helimagnet FeGe studied by small-angle neutron scattering

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