Superconductor/semiconductor nanostructures on p-type InAs

Chrestin, A.; Kürsten, Rüdiger; Biedermann, K.; Matsuyama, T.; Merkt, U.

doi:10.1006/spmi.1999.0719

Cited by 15 publications

(11 citation statements)

References 24 publications

(29 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such structures, reviewed in Ref. [25], have been realized by contacting InAs surface inversion layers [26,27] We show how to design and control MBS in a pS system with a stripe of the superconducting layer removed to form an effective one-dimensional topological supercon- ductor. This forms a pS-N-pS junction as sketched in Fig.…”

mentioning

confidence: 99%

Two-Dimensional Platform for Networks of Majorana Bound States

2017

View full text Add to dashboard Cite

We model theoretically a two-dimensional electron gas (2DEG) covered by a superconductor and demonstrate that topological superconducting channels are formed when stripes of the superconducting layer are removed. As a consequence, Majorana bound states (MBS) are created at the ends of the stripes. We calculate the topological invariant and energy gap of a single stripe, using realistic values for an InAs 2DEG proximitized by an epitaxial Al layer. We show that the topological gap is enhanced when the structure is made asymmetric. This can be achieved by either imposing a phase difference (by driving a supercurrent or using a magnetic-flux loop) over the strip or by replacing one superconductor by a metallic gate. Both strategies also enable control over the MBS splitting, thereby facilitating braiding and readout schemes based on controlled fusion of MBS. Finally, we outline how a network of Majorana stripes can be designed.PACS numbers: 71.10. Pm, 74.50.+r, Majorana bound states (MBS) are states localized at the edges of topological superconductors [1][2][3][4]. They have nonlocal properties that may be utilized for storage and manipulation of quantum information in a topologically protected way [5][6][7]. However, the realization of MBS requires superconducting p-wave pairing, which appears only in exotic materials. Therefore, there is currently a search for ways to engineer p-wave pairing by combining s-wave superconductors with strong spinorbit materials. Recent experiments looked for evidence of MBS in, for example, semiconducting nanowires [8][9][10][11][12][13][14], topological insulators [15], and magnetic atom chains [16, 17]. These systems may also allow demonstration experiments of the nonlocal properties of MBS, for example using recent suggestions for controlling MBS in prototypical architectures [18][19][20][21][22][23]. However, to go beyond basic demonstration experiments a scalable and flexible platform for large-scale MBS networks is needed.Here, we suggest one such flexible platform based on a two-dimensional electrons gas (2DEG) with strong spinorbit coupling in proximity to a superconductor [24]. Such structures, reviewed in Ref. [25], have been realized by contacting InAs surface inversion layers [26,27] We show how to design and control MBS in a pS system with a stripe of the superconducting layer removed to form an effective one-dimensional topological supercon- ductor. This forms a pS-N-pS junction as sketched in Fig. 1(a), which can be fabricated by standard lithographic techniques. We show, similar to other semiconductorbased setups [34][35][36][37][38], that this system undergoes several topological phase transitions when increasing a magnetic field parallel to the stripe for parameters readily available in the lab. We base our findings on a numerical tightbinding calculation of the energy spectrum, the topological invariant, as well as transport calculations [33]. We discuss how the topological energy gap depends on various parameters, which is vital for the topological protection ...

show abstract

mentioning

confidence: 99%

Two-Dimensional Platform for Networks of Majorana Bound States

2017

View full text Add to dashboard Cite

show abstract

“…In a number of experiments, the current-voltage characteristics (IVCs) were measured in superconductor-normal metal-superconductor (SNS) junctions consisting of a highmobility two-dimensional electron gas (2DEG) connected to two bulk superconducting electrodes [1][2][3][4][5][6]. In these devices, the electrodes have a large width w up to 40 μm, whereas the distance L between the electrodes varies between 0.2 and 1 μm.…”

Section: Introductionmentioning

confidence: 99%

“…This is comparable or larger than the coherence length ξ N =hv F / , where v F is the Fermi velocity in the 2DEG but much smaller than the elastic-and inelastic-scattering lengths. These junctions show well-pronounced Josephson effect and have rather small NS interface resistances which correspond to a large transmission coefficient of ∼ 0.8 [4,6].…”

Section: Introductionmentioning

confidence: 99%

Resonant subgap current transport in Josephson field effect transistor

2017

View full text Add to dashboard Cite

We study theoretically the current-voltage characteristics (IVCs) of the Josephson field effect transistor-a ballistic SNINS junction with superconducting (S) electrodes confining a planar normal-metal region (N), which is controlled by the gate-induced potential barrier (I). Using the computation technique developed earlier for long single-channel junctions in the coherent multiple Andreev reflection (MAR) regime, we find a significant difference of the subgap current structure compared to the subharmonic gap structure in tunnel junctions and atomic-size point contacts. For long junctions, whose lengths significantly exceed the coherence length, the IVC exhibits current peaks at multiples (harmonics) of the distance δ m between the static Andreev levels eV n = nδ m . Moreover, the averaged IVC follows the powerlike behavior rather than the exponential one and has a universal scaling with the junction transparency. This result is qualitatively understood using an analytical approach based on the concept of resonant MAR trajectories. In shorter junctions having lengths comparable to the coherence length, the IVC has an exponential form common for point contacts, however the current structures appear at the subharmonics of the interlevel distance eV n = δ m /n rather than the gap subharmonics 2 /n.

show abstract

“…T c values in the range of 24-39 K were usually achieved in thin films prepared by these methods. However, the rather high processing temperatures used during these methods are unsuitable for multilayer or heterostructure device fabrication in systems where interfacial chemical reactions or diffusion at the interfaces during preparation is disastrous for device function-ing, e.g., in superconductor/semiconductor hybrids [26][27][28][29][30] and superconductor/ferromagnetic metal proximity-related heterostructures [31,32]. Furthermore, the difficulty in thin film preparation at high temperatures is related to the high vapor pressure and volatility of Mg, starting even at modest temperatures.…”

Section: Introductionmentioning

confidence: 99%

As-grown superconducting MgB₂thin films prepared at extreme deposition conditions

Sahoo

Keune

Kuncser

et al. 2011

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Superconducting (SC) MgB 2 thin films were prepared in situ in one step by vacuum co-deposition at extremely low growth temperature (T s ∼ 110-150 • C) and at very low Mg deposition rate, far off from the MgB 2 stability regime of the thermodynamic phase diagram. As-grown films are nanocrystalline and exhibit (002) texture, moderate surface roughness and SC onset up to T on c = 18 K. This is the highest critical temperature ever observed in low-T s as-grown MgB 2 films. Our preparation method at very low T s is favorable for the fabrication of layered SC hybrid electronic devices, where deposition and post-annealing at high temperature are detrimental to device functioning. Simple post-annealing of our films in ultrahigh vacuum enhances T on c up to 22 K due to the improvement in structural properties.

show abstract

Superconductor/semiconductor nanostructures on p-type InAs

Cited by 15 publications

References 24 publications

Two-Dimensional Platform for Networks of Majorana Bound States

Two-Dimensional Platform for Networks of Majorana Bound States

Resonant subgap current transport in Josephson field effect transistor

As-grown superconducting MgB₂thin films prepared at extreme deposition conditions

Contact Info

Product

Resources

About

Superconductor/semiconductor nanostructures on p-type InAs

Cited by 15 publications

References 24 publications

Two-Dimensional Platform for Networks of Majorana Bound States

Two-Dimensional Platform for Networks of Majorana Bound States

Resonant subgap current transport in Josephson field effect transistor

As-grown superconducting MgB2thin films prepared at extreme deposition conditions

Contact Info

Product

Resources

About

As-grown superconducting MgB₂thin films prepared at extreme deposition conditions