Enhanced Majorana bound states in magnetic chains on superconducting topological insulator edges

Teixeira, Raphael L. R. C.; Kuzmanovski, Dushko; Black‐Schaffer, Annica M.; Silva, Luis G. G. V. Dias da

doi:10.1103/physrevb.102.165312

Cited by 7 publications

(3 citation statements)

References 40 publications

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“…Figures 10 (a-b) depict the spin-resolved current distribution in the device at T=100 K and 𝑉 𝐷𝑆 =0.05 V. As expected, the spin-down carriers mainly move forward, and spin-up carriers move backward in one half of the ribbon. A similar system consisting of a magnetic chain deposited on a 2D TI edge in proximity to a superconductor was studied using a Kane-Mele Hamiltonian in [40]. It was suggested that such an arrangement results in highly localized Majorana bound states at the ends of the magnetic chain [40].…”

Section: Transport Properties Of Bismuthene Nanoribbon With Magnetism...mentioning

confidence: 99%

“…A similar system consisting of a magnetic chain deposited on a 2D TI edge in proximity to a superconductor was studied using a Kane-Mele Hamiltonian in [40]. It was suggested that such an arrangement results in highly localized Majorana bound states at the ends of the magnetic chain [40]. The zigzag ribbons suggested here and in the previous section can be good candidates for designing such topological superconductors, as only two channels with opposite spins and opposite directions are present, resulting in one Majorana bound state at each end of the structure.…”

Section: Transport Properties Of Bismuthene Nanoribbon With Magnetism...mentioning

confidence: 99%

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Spin Filtering Properties of Structures Based on Stanene and Bismuthene Nanoribbons with Magnetism

Akhoundi,

Houssa,

Afzalian

2023

Preprint

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The transport properties of spin filters based on two-dimensional magnetic topological insulators (TI) are theoretically studied, exploiting the spin-polarized quantum-anomalous-Hall effect in these materials. The electron transport properties of these structures are explored through the non-equilibrium-Green’s-functon(NEGF) formalism. We first considered the spin-filtering properties of heterostructures based on non-magnetic TI/antiferromagnetic TI heterostructures, using a Kane-Mele tight-binding Hamiltonian model. Our results reveal that a gate bias of about 2 V is required to obtain an order of magnitude drop in the minority spin current of these heterostructures. In a search for magnetic TIs suitable for these applications, we investigate the electronic and magnetic properties of stanene and bismuthene nanoribbons with metal edge modification, using density functional theory (DFT) simulations. The direction of the magnetic moment is found to be heavily influenced by the electric field, while the magnitude of the magnetic moment declines drastically. Additionally, the role of edge oxidization on the magnetic state of stanene nanoribbons is explored, and a noticeable impact is observed. We next study the spin filtering properties of stanene and bismuthene ribbons with magnetism only at one edge, using NEGF based on DFT Hamiltonians. The transport characteristics exhibit noticeable spin polarization, without requiring an applied electric field along the out-of-plane direction. We also show that one edge magnetization can be induced in stanene nanoribbons with asymmetric edge passivation; DFT simulations predict the formation of one-way helical edge states in these structures. The results presented herein provide insight into the transport properties of magnetic TIs and their possible applications in spin filters and qubits based on Majorana bound states.

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Section: Transport Properties Of Bismuthene Nanoribbon With Magnetism...mentioning

confidence: 99%

Section: Transport Properties Of Bismuthene Nanoribbon With Magnetism...mentioning

confidence: 99%

Spin Filtering Properties of Structures Based on Stanene and Bismuthene Nanoribbons with Magnetism

Akhoundi,

Houssa,

Afzalian

2023

Preprint

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“…In recent times, much attention has been directed at an alternative proposal, where a TSC phase can be realized in a chain of magnetic impurities placed on the surface of a s-wave superconductor [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]. Physically, magnetic impurities placed on a conventional superconductor give rise to Yu-Shiba-Rusinov (YSR) states [54][55][56][57].…”

Section: Introductionmentioning

confidence: 99%

Tailoring phase transition from topological superconductor to trivial superconductor induced by magnetic textures of a spin-chain on a $p$-wave superconductor

Chatterjee¹,

Pradhan²,

Nandy³

et al. 2022

Preprint

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We theoretically investigate the phase transition from a non-trivial topological p-wave superconductor to a trivial s-wave like superconducting phase through a gapless phase, driven by different magnetic textures as an one-dimensional spin-chain impurity, e.g., Bloch-type, in-plane and out-ofplane Néel-type spin-chains etc. In our proposal, the chain of magnetic impurities is placed on a spin-triplet p-wave superconductor where we obtain numerically as well as analytically an effective s-wave like pairing due to spin rotation, resulting in gradual destruction of the Majorana zero modes present in the topological superconducting phase. In particular, when the impurity spins are antiferromagnetically aligned i.e., spiral wave vector Gs = π, the system becomes an effective s-wave superconductor without Majorana zero modes in the local density of states. The Shiba bands, on the other hand, formed due to the overlapping of Yu-Shiba-Rusinov states play a crucial role in this topological to trivial superconductor phase transition, confirmed by the sign change in the minigap within the Shiba bands. Moreover, interference of the Shiba bands exhibiting oscillatory behavior within the superconducting gap, −∆p to ∆p, as a function of Gs, also reflects an important evidence for the formation of an effective s-wave pairing. Such oscillation is absent in the p-wave regime. Our study paves the way to foresee the stability and tunability of topological superconducting phase via controlled manipulation of the spin spiral configurations of the magnetic impurity chain.

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Multiple topological phase transitions unveiling gapless topological superconductivity in magnet/unconventional superconductor hybrid platform

Subhadarshini,

Pal,

Chatterjee

et al. 2024

Applied Physics Letters

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We propose a theoretical framework for generating gapless topological superconductivity (GTSC) hosting Majorana flat edge modes (MFEMs) in the presence of a two-dimensional (2D) array of magnetic adatoms with noncollinear spin texture deposited on top of an unconventional superconductor. Our observations reveal two distinct topological phase transitions within the emergent Shiba band depending on the exchange coupling strength (J) between magnetic adatom spins and superconducting electrons: the first one designates transition from gapless non-topological to gapless topological phase at lower J, while the second one denotes transition from gapless topological to a trivial gapped superconducting phase at higher J. The gapless topological superconducting phase survives at intermediate values of J, hosting MFEMs. Furthermore, we investigate the nature of the bulk effective pairings, which indicate that GTSC appears due to the interplay between pseudo “s-wave” and pseudo “px+py” types of pairing. Consequently, our study opens a promising avenue for the experimental realization of GTSC in 2D Shiba lattice based on d-wave superconductors as a high-temperature platform.

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Enhanced Majorana bound states in magnetic chains on superconducting topological insulator edges

Cited by 7 publications

References 40 publications

Spin Filtering Properties of Structures Based on Stanene and Bismuthene Nanoribbons with Magnetism

Spin Filtering Properties of Structures Based on Stanene and Bismuthene Nanoribbons with Magnetism

Tailoring phase transition from topological superconductor to trivial superconductor induced by magnetic textures of a spin-chain on a $p$-wave superconductor

Multiple topological phase transitions unveiling gapless topological superconductivity in magnet/unconventional superconductor hybrid platform

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