Synthetic spin–orbit interaction for Majorana devices

Desjardins, Matthieu; Contamin, Lauriane; Delbecq, Matthieu; Dartiailh, Matthieu; Bruhat, Laure; Cubaynes, Tino; Viennot, Jeremie; Mallet, François; Rohart, Stanislas; Thiaville, A.; Cottet, Audrey; Kontos, Takis

doi:10.1038/s41563-019-0457-6

Cited by 115 publications

(74 citation statements)

References 34 publications

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“…The electrically-induced switching of the stripes orientation offers an additional knob not only for investigating the nature of the ZBCP and its relation to the presence of MBS, but also for exploring their robustness as a function of tunable synthetic SOC. Furthermore, the proposed set-up could provide a proof-of-concept demonstration of the feasibility of using electrically-controlled synthetic SOC for the manipulation of MBS beyond recent experimental advances [45], paving the way to more complex platforms with extended tunability for the realization of braiding operations [42,43].…”

Section: Discussion and Summarymentioning

confidence: 99%

Electrical Control of Majorana Bound States Using Magnetic Stripes

Mohanta

Zhou

et al. 2019

Phys. Rev. Applied

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A hybrid semiconductor-superconductor nanowire on the top of a magnetic film in the stripe phase experiences a magnetic texture from the underlying fringing fields. The Zeeman interaction with the highly inhomogeneous magnetic textures generates a large synthetic spin-orbit coupling. We show that this platform can support the formation of Majorana bound states (MBS) localized at the ends of the nanowire. The transition to the topological superconducting phase not only depends on the nanowire parameters and stripe size but also on the relative orientation of the stripes with respect to the nanowire axis. Topological phase transitions with the corresponding emergence or destruction of MBS can be induced by reorienting the stripes or shifting their position, which can be achieved by passing a charge current through the magnetic film or by applying electrically-controlled strain to it. The proposed platform removes the need for external magnetic fields and offers a non-invasive electrical tuning of MBS with the perturbation (current or strain) acting only on thee magnetic film.

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Section: Discussion and Summarymentioning

confidence: 99%

Electrical Control of Majorana Bound States Using Magnetic Stripes

Mohanta

Zhou

et al. 2019

Phys. Rev. Applied

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“…For example, state-of-the art fabrication of superconducting junctions with topological insulators [38] would support fabrication of similar X-shaped junctions. With the progress in tunable magnetic textures used to modify proximity-induced superconductivity [23,27,[39][40][41][42][43][44][45][46][47][48][49], X-shaped junctions could be considered with a reduced role of an applied magnetic field.…”

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confidence: 99%

Phase Control of Majorana Bound States in a Topological X Junction

et al. 2020

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Topological superconductivity supports exotic Majorana bound states (MBS) which are chargeless zeroenergy emergent quasiparticles. With their non-Abelian exchange statistics and fractionalization of a single electron stored nonlocally as a spatially separated MBS, they are particularly suitable for implementing fault-tolerant topological quantum computing. While the main efforts to realize MBS have focused on one-dimensional systems, the onset of topological superconductivity requires delicate parameter tuning and geometric constraints pose significant challenges for their control and demonstration of non-Abelian statistics. To overcome these challenges, building on recent experimental advances in planar Josephson junctions (JJs), we propose a MBS platform of X-shaped JJs. This versatile implementation reveals how external flux control of the superconducting phase difference can generate and manipulate multiple MBS pairs to probe non-Abelian statistics. The underlying topological superconductivity exists over a large parameter space, consistent with materials used in our fabrication of such X junctions, as an important step towards scalable topological quantum computing. arXiv:1909.05386v1 [cond-mat.mes-hall]

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“…An alternative approach to engineering topological superconductors while circumventing these two challenges could be to remove the spin-orbit coupling ingredient, and instead consider a non-collinear magnetic texture proximitized by a conventional superconductor 14,[25][26][27][28][29] . In fact, our results are relevant for a broader class of skyrmion-like textures, such as magnetic bubbles [30][31][32][33] .…”

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confidence: 99%

Topological superconductivity with deformable magnetic skyrmions

2019

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Magnetic skyrmions are nanoscale spin configurations that are efficiently created and manipulated. They hold great promises for next-generation spintronics applications. In parallel, the interplay of magnetism, superconductivity and spin-orbit coupling has proved to be a versatile platform for engineering topological superconductivity predicted to host non-abelian excitations, Majorana zero modes. We show that topological superconductivity can be induced by proximitizing skyrmions and conventional superconductors, without need for additional ingredients. Apart from a previously reported Majorana zero mode in the core of the skyrmion, we find a more universal chiral band of Majorana modes on the edge of the skyrmion. We show that the chiral Majorana band is effectively flat in the physically relevant parameter regime, leading to interesting robustness and scaling properties. In particular, the number of Majorana modes in the (nearly-)flat band scales with the perimeter length of the system, while being robust to local disorder. 1 arXiv:1904.03005v3 [cond-mat.supr-con] 23 Oct 2019 8 where all energies are in units of the bandwidth t, all distances are in units of the lattice spacing a (see Supplementary Note 1 and Supplementary Figure 1 for details). For precisely |m J | = |m * J | the wire is at the topological transition and has a gapless spectrum, giving our model a bulk-gap-closing point as shown in Fig. 2c.The MFB found here has a protection by a chiral symmetry, as MFB's were found to have in models with translational symmetries 39,40,51 . Note that the wire Hamiltonian and its MFB become a correct model for our texture Eq. (1) if we choose q = 0 and thereby nullify the H slope m J (r) term. Physically, this is a special case where instead of the skyrmion shape the texture becomes coplanar (in the xz-plane, see Eq. (1)), and the orthogonal direction provides a chiral operator Ξ = τ y σ ythat anticommutes with the Hamiltonian (see Eq. (2)). Since all the MFB states have the same chirality, they cannot hybridize among themselves. It is difficult to remove the MFB states 51 , namely, a perturbation must have energy larger than the effective gap; or, it should hybridize the MFB with low energy bulk states at |m J | ≈ |m * J |, which are few; or, chirality symmetry must be broken (out-of-xz-plane exchange field). We note that the proof of existence of the MFB rests on the rotational symmetry of the q = 0 coplanar texture, since this symmetry provides the m J quantum number. Consider now deformations of the shape of the edge imposed on our q = 0 coplanar texture. These geometric deformations would generally mix the m J sectors, yet the described stability of the MFB implies that the deformations would be inefficient in removing the MFB states.We can now proceed to the relevant model for a skyrmion with arbitrary q = 0:The single term H slope m J (r) breaks the chiral symmetry Ξ, and there are no other chiral operators. The term H slope m J (r) exactly contributes an energy ε edgestate (m J ) ∼ m J to an MFB state ...

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Synthetic spin–orbit interaction for Majorana devices

Cited by 115 publications

References 34 publications

Electrical Control of Majorana Bound States Using Magnetic Stripes

Electrical Control of Majorana Bound States Using Magnetic Stripes

Phase Control of Majorana Bound States in a Topological X Junction

Topological superconductivity with deformable magnetic skyrmions

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