High-Temperature Majorana Corner States

Wang, Qiyue; Liu, Cheng-Cheng; Lü, Yuan; Zhang, Fan

doi:10.1103/physrevlett.121.186801

Cited by 265 publications

(177 citation statements)

References 109 publications

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“…It induces a pairing gap at the edge states. The gap may switch sign at the corners, giving rise to Majorana corner modes [3][4][5]. This is the essence of the SOTS.…”

Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

“…Introduction.-The second-order topological superconductor (SOTS) is a novel topological phase of matter and features Majorana zero-dimensional (0D) corner or 1D hinge states which are two dimensions lower than the gapped bulk [1][2][3][4][5][6][7][8][9][10][11][12] and may provide stable qubits for topological quantum computation [13][14][15][16][17][18][19][20][21]. Recently, the SOTS has been discovered in a variety of realistic materials and triggered tremendous interest [3][4][5][6][7][8][9][10][22][23][24][25][26][27]. One way to mimic SOTSs in 2D is given by quantum spin Hall insulators (QSHIs) in proximity to unconventional superconductors with d x 2 −y 2 -wave or s ± -wave pairing order [3][4][5].…”

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confidence: 99%

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Detection of second-order topological superconductors by Josephson junctions

Zhang

Trauzettel

2020

Phys. Rev. Research

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We study Josephson junctions based on a second-order topological superconductor (SOTS) which is realized in a quantum spin Hall insulator with a large inverted gap in proximity to an unconventional superconductor. We find that tuning the chemical potential in the superconductor strongly modifies the pairing gap of the helical edge states and leads to topological phase transitions. As a result, the supercurrent in the junction is controllable and a 0-π transition is realized by tuning the chemical potentials in the superconducting leads. These striking features are stable in junctions with different sizes, doping in the normal region, and in the presence of disorder. We propose them as novel experimental signatures of SOTSs. Moreover, the 0-π transition can serve as a fully electric way to create or annihilate Majorana bound states in the junction without magnetic manipulation.Introduction.-The second-order topological superconductor (SOTS) is a novel topological phase of matter and features Majorana zero-dimensional (0D) corner or 1D hinge states which are two dimensions lower than the gapped bulk [1-12] and may provide stable qubits for topological quantum computation [13][14][15][16][17][18][19][20][21]. Recently, the SOTS has been discovered in a variety of realistic materials and triggered tremendous interest [3][4][5][6][7][8][9][10][22][23][24][25][26][27]. One way to mimic SOTSs in 2D is given by quantum spin Hall insulators (QSHIs) in proximity to unconventional superconductors with d x 2 −y 2 -wave or s ± -wave pairing order [3][4][5]. The proximity effect of unconventional superconductivity in 2D systems has also been intensively explored in theory [28][29][30][31][32][33][34][35][36][37] and experiment [38][39][40][41][42][43]. To date, however, the only way proposed to detect 2D SOTSs is a tunneling experiment without a concrete calculation of the observable signature. An alternative or complementary approach to probe SOTSs and manipulate the Majorana corner modes is thus desirable. In QSHIs, a finite doping is usually inevitable, and the chemical potential can be far away from the Dirac points. Therefore, it is interesting and relevant to explore the influence of the chemical potential in SOTSs.

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“…It induces a pairing gap at the edge states. The gap may switch sign at the corners, giving rise to Majorana corner modes [3][4][5]. This is the essence of the SOTS.…”

Section: Arxiv:190509308v1 [Cond-matsupr-con] 22 May 2019mentioning

confidence: 99%

mentioning

confidence: 99%

Detection of second-order topological superconductors by Josephson junctions

Zhang

Trauzettel

2020

Phys. Rev. Research

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“…In second-order TSCs these MZMs have been studied at the corners of a two-dimensional (2D) system and hinges of a three-dimensional (3D) system where neighboring hinges have different chiralities 27,28 . These zero-energy corner modes are known as Majorana corner states (MCSs) which have been studied in various kinds of system such as high-temperature superconductors (SCs) [29][30][31][32][33][34] , s-wave superfluid 28,35 , systems with an external magnetic field [36][37][38] , and 2D and 3D second-order TSCs 39 .…”

Section: Introductionmentioning

confidence: 99%

Majorana corner flat bands in two-dimensional second-order topological superconductors

et al. 2020

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In this paper we find that confining a second-order topological superconductor with a harmonic potential leads to a proliferation of Majorana corner modes. As a consequence, this results in the formation of Majorana corner flat bands which have a fundamentally different origin from that of the conventional mechanism. This is due to the fact that they arise solely from the one-dimensional gapped boundary states of the hybrid system that become gapless without the bulk gap closing under the increase of the trapping potential magnitude. The Majorana corner states are found to be robust against the strength of the harmonic trap and the transition from Majorana corner states to Majorana flat bands is merely a smooth crossover. As a harmonic trap can potentially be realized in heterostructures, this proposal paves a way to observe these Majorana corner flat bands in an experimental context.

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“…However, the conductance oscillation can be induced by AC of CEMs propagating through the SC/QH (or QAH) interface in the ballistic regime [43,44], which is sensitive to elastic scattering. Therefore, understanding disorder effect in the SC/QH(QAH) junctions [45,46] is essential for any reliable theoretical interpretation.…”

Section: Introductionmentioning

confidence: 99%

Quantum perfect crossed Andreev reflection in top-gated quantum anomalous Hall insulator–superconductor junctions

et al. 2017

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We investigate the quantum tunneling and Andreev reflection in a top-gated quantum anomalous Hall insulator proximity-coupled with a superconductor junction. A quantized perfect crossed Andreev reflection with its coefficient being integer 1 is obtained and all other scattering processes (the normal reflection, normal tunneling and local Andreev reflection) are completely suppressed, when the topological superconductor phase with Chern number N = 1 is realized. This perfect crossed Andreev reflection originates from the tunneling of the chiral Majorana edge states, and the phase of tunneling amplitude only being 0 and π plays a decisive role. Furthermore, because of the chiral characteristic of the Majorana edge states, the perfect crossed Andreev reflection is robust against the disorder and can work in a wide range of system parameters.

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High-Temperature Majorana Corner States

Cited by 265 publications

References 109 publications

Detection of second-order topological superconductors by Josephson junctions

Detection of second-order topological superconductors by Josephson junctions

Majorana corner flat bands in two-dimensional second-order topological superconductors

Quantum perfect crossed Andreev reflection in top-gated quantum anomalous Hall insulator–superconductor junctions

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