Prevalence of trivial zero-energy subgap states in nonuniform helical spin chains on the surface of superconductors

Hess, Richard; Legg, Henry F.; Loss, Daniel; Klinovaja, Jelena

doi:10.1103/physrevb.106.104503

Cited by 9 publications

(2 citation statements)

References 131 publications

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“…STM spectroscopy of chains that exhibit signatures of zero-energy end states also show residual in-gap states along the chain, obstructing the identification of a topological bulk gap [61]. Theoretical studies have addressed mechanisms for the appearance of trivial zero-energy end states [107,108].…”

Section: Experimental Searches and Lessons Learnedmentioning

confidence: 99%

Hunting for Majoranas

Yazdani

Oppen

Halperin

et al. 2023

Science

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Over the past decade, there have been considerable efforts to observe non-abelian quasiparticles in novel quantum materials and devices. These efforts are motivated by the goals of demonstrating quantum statistics of quasiparticles beyond those of fermions and bosons and of establishing the underlying science for the creation of topologically protected quantum bits. In this Review, we focus on efforts to create topological superconducting phases that host Majorana zero modes. We consider the lessons learned from existing experimental efforts, which are motivating both improvements to present platforms and the exploration of new approaches. Although the experimental detection of non-abelian quasiparticles remains challenging, the knowledge gained thus far and the opportunities ahead offer high potential for discovery and advances in this exciting area of quantum physics.

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Section: Experimental Searches and Lessons Learnedmentioning

confidence: 99%

Hunting for Majoranas

Yazdani

Oppen

Halperin

et al. 2023

Science

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show abstract

“…The lack of a conclusive experimental observation has led to the suggestion of several auxiliary features in nanowire devices that could indicate the onset of a topological phase. Examples include looking for correlated zero-bias peaks, oscillations around zero energy due to a finite overlap of the MBSs in short nanowires [32][33][34][35][36], the flip of the spin polarization in the lowest band [37,38], a quantized conductance peak with height 2e 2 /h [39][40][41][42][43], and using non-local conductance to observe the bulk gap closing and reopening associated with the topological phase transition [31,[44][45][46][47][48][49][50][51][52][53][54].…”

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confidence: 99%

Parity protected superconducting diode effect in topological Josephson junctions

Legg¹,

Laubscher²,

Loss³

et al. 2023

Preprint

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In bulk superconductors or Josephson junctions formed in materials with spin-orbit interaction, the critical current can depend on the direction of current flow and applied magnetic field, an effect known as the superconducting (SC) diode effect. Here, we consider the SC diode effect in Josephson junctions in nanowire devices. We find that the 4π-periodic contribution of Majorana bound states (MBSs) to the current phase relation (CPR) of single junctions results in a significant enhancement of the SC diode effect when the device enters the topological phase. Crucially, this enhancement of the SC diode effect is independent of the parity of the junction and therefore protected from parity altering events, such as quasiparticle poisoning, which have hampered efforts to directly observe the 4π-periodic CPR of MBSs. We show that this effect can be generalized to SQUIDs and that, in such devices, the parity-protected SC diode effect can provide a highly controllable probe of the topology in a Josephson junction.

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Majorana bound states with chiral magnetic textures

Güngördü

Kovalev

2022

Journal of Applied Physics

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The aim of this Tutorial is to give a pedagogical introduction into realizations of Majorana fermions, usually termed as Majorana bound states (MBSs), in condensed matter systems with magnetic textures. We begin by considering the Kitaev chain model of “spinless” fermions and show how two “half” fermions can appear at chain ends due to interactions. By considering this model and its two-dimensional generalization, we emphasize intricate relation between topological superconductivity and possible realizations of MBS. We further discuss how “spinless” fermions can be realized in more physical systems, e.g., by employing the spin-momentum locking. Next, we demonstrate how magnetic textures can be used to induce synthetic or fictitious spin–orbit interactions, and, thus, stabilize MBS. We describe a general approach that works for arbitrary textures and apply it to skyrmions. We show how MBS can be stabilized by elongated skyrmions, certain higher order skyrmions, and chains of skyrmions. We also discuss how braiding operations can be performed with MBS stabilized on magnetic skyrmions. This Tutorial is aimed at students at the graduate level.

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Prevalence of trivial zero-energy subgap states in nonuniform helical spin chains on the surface of superconductors

Cited by 9 publications

References 131 publications

Hunting for Majoranas

Hunting for Majoranas

Parity protected superconducting diode effect in topological Josephson junctions

Majorana bound states with chiral magnetic textures

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