Domain wall motion in junctions of thin-film magnets and topological insulators

Ferreirós, Yago; Cortijo, Alberto

doi:10.1103/physrevb.89.024413

Cited by 27 publications

(36 citation statements)

References 28 publications

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“…It was described in Ref. [55], where they made use of an electric field to tune the chirality through the mechanism explained above, while here we have shown that it can be done also by applying a gate voltage.…”

Section: A Equilibrium Configuration Of the Dwmentioning

confidence: 66%

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Dirac electrons and domain walls: A realization in junctions of ferromagnets and topological insulators

2015

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We study a system of Dirac electrons with finite density of charge carriers coupled to an external electromagnetic field in two spatial dimensions, with a domain wall (DW) mass term. The interface between a thin-film ferromagnet and a three-dimensional topological insulator provides a condensed-matter realization of this model, when an out-of-plane domain wall magnetization is coupled to the topological insulator surface states. We show how, for films with very weak intrinsic in-plane anisotropies, the torque generated by the edge electronic current flowing along the DW competes with an effective in-plane anisotropy energy, induced by quantum fluctuations of the chiral electrons bound to the wall, in a mission to drive the internal angle of the DW from a Bloch configuration towards a Néel configuration. Both the edge current and the induced anisotropy contribute to stabilize the internal angle, so that for weak intrinsic in-plane anisotropies DW motion is still possible without suffering from an extremely early Walker breakdown.

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Section: A Equilibrium Configuration Of the Dwmentioning

confidence: 66%

“…It was first suggested in Ref. [55], where an electric field was needed, and afterwards in Ref. [56], where it was shown that a similar effect could be achieved in equilibrium.…”

Section: B Current Induced Magnetization Dynamicsmentioning

confidence: 97%

Dirac electrons and domain walls: A realization in junctions of ferromagnets and topological insulators

2015

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“…A magnetic domain wall in proximity to the Dirac electron generates a chiral state, in analogy to the Jackiw-Rebbi zero mode 13 , which in turn alters its dynamics and stability [14][15][16][17] . One could thus expect more novel properties when the Dirac states of a TI couple to nontrivial spin textures, such as skyrmions 18,19 , which is the main issue of this work.…”

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confidence: 99%

Charged skyrmions on the surface of a topological insulator

et al. 2015

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We consider the interplay between magnetic skyrmions in an insulating thin film and the Dirac surface states of a 3D topological insulator (TI), coupled by proximity effect. The magnetic texture of skyrmions can lead to confinement of Dirac states at the skyrmion radius, where out of plane magnetization vanishes. This confinement can result in charging of the skyrmion texture. The presence of bound states is robust in an external magnetic field, which is needed to stabilize skyrmions. It is expected that for relevant experimental parameters skyrmions will have a few bound states that can be tuned using an external magnetic field. We argue that these charged skyrmions can be manipulated directly by an electric field, with skyrmion mobility proportional to the number of bound states at the skyrmion radius. Coupling skyrmionic thin films to a TI surface can provide a more direct and efficient way of controlling skyrmion motion in insulating materials. This provides a new dimension in the study of skyrmion manipulation.

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“…It should be noted that, although their effect is negligible on the bulk propagation of light, the 1D Fermi arc chiral states at the edges of a WSM would give additional resonances as surface electromagnetic modes. However, the polarization tensor of 1D chiral electrons has already been computed in the literature 47,48 and therefore the Fermi arc contribution can be distinguished from bulk propagation.…”

Section: Discussion and Conclussionsmentioning

confidence: 99%

Unconventional electromagnetic mode in neutral Weyl semimetals

Ferreirós

Cortijo

2016

Phys. Rev. B

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We study light propagation in a neutral Weyl semimetal with the Fermi level lying at the Weyl nodes in the weak self-interacting regime. The nontrivial topology induces a screening effect in one of the two transverse gauge fields, for which we find two branches of attenuated collective excitations. In addition to the known topologically gaped photon mode, a novel massless and slightly damped excitation appears. Strikingly, at low energies this new excitation has a linear dispersion and it propagates with the same velocity than the electrons, while at energies well above the electron-hole continuum threshold it behaves as a massive attenuated photon with velocity similar to the speed of light in the material. There is a crossover at certain momentum in the direction perpendicular to the separation of the Weyl nodes above which the novel gapless mode enters into an overdamped regime. Regarding the unscreened gauge field we show that it is also attenuated, which is a non-topological property shared by Dirac semimetals as well.

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Domain wall motion in junctions of thin-film magnets and topological insulators

Cited by 27 publications

References 28 publications

Dirac electrons and domain walls: A realization in junctions of ferromagnets and topological insulators

Dirac electrons and domain walls: A realization in junctions of ferromagnets and topological insulators

Charged skyrmions on the surface of a topological insulator

Unconventional electromagnetic mode in neutral Weyl semimetals

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