Spin-polarized edge currents and Majorana fermions in one- and two-dimensional topological superconductors

AbstractMajorana fermions, as electronic quasi-particle modes in solid states, have been under the focus of research due to their exotic physical properties. While the evidence of Majorana fermions as zero-dimensional bound states has been well established, the existence of one-dimensional Majorana modes is still under debate. The main reason is that the current theoretical proposals of platforms supporting such states are very challenging experimentally. Here, we propose a method to create two-dimensional topological superconductors with a heterostructure of ferromagnet, topological insulator thin film and superconductor. We show that such a system supports one-dimensional chiral Majorana edge modes in a wide range of parameters which is readily achievable in experiments. We further propose a new transport measurement to detect these modes.

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Polygon sign rules of Majorana fermions in two-dimensional topological superconductors

International Journal of Modern Physics B ◽

10.1142/s0217979216502131 ◽

2016 ◽

Vol 30 (27) ◽

pp. 1650213

Author(s):

Qiu-Bo Cheng ◽

Jing He ◽

Jing Yu ◽

Xiao-Ming Zhao ◽

Su-Peng Kou

Keyword(s):

Quantum Computation ◽

Numerical Approach ◽

Majorana Fermions ◽

Two Dimensional ◽

Line Defect ◽

Topological Superconductor ◽

Topological Superconductors ◽

Topological Quantum ◽

Different Types ◽

Topological Quantum Computation

Recently, Majorana fermions (MFs) have attracted intensive attention due to their exotic statistics and possible applications in topological quantum computation. They are proposed to exist in various two-dimensional (2D) topological systems, such as [Formula: see text] topological superconductor (SC) and nanowire–superconducting hybridization system. In this paper, we point out that Majorana fermions in different topological systems obey different types of polygon sign rules. A numerical approach is described to identify the type of polygon sign rule of the Majorana fermions. Applying the approach to study two 2D topological systems, we find that vortex-induced Majorana fermions obey topological polygon sign rule and line-defect-induced Majorana fermions obey normal polygon sign rule.

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Topological Edge States of a Majorana BBH Model

Condensed Matter ◽

10.3390/condmat6020015 ◽

2021 ◽

Vol 6 (2) ◽

pp. 15

Author(s):

Alfonso Maiellaro ◽

Roberta Citro

Keyword(s):

2D Materials ◽

Finite Size ◽

Majorana Fermions ◽

Topological Phase ◽

Two Dimensional ◽

Edge States ◽

Finite Size Scaling ◽

Topological Properties ◽

Berry Curvature ◽

Topological Superconductors

We investigate a Majorana Benalcazar–Bernevig–Hughes (BBH) model showing the emergence of topological corner states. The model, consisting of a two-dimensional Su–Schrieffer–Heeger (SSH) system of Majorana fermions with π flux, exhibits a non-trivial topological phase in the absence of Berry curvature, while the Berry connection leads to a non-trivial topology. Indeed, the system belongs to the class of second-order topological superconductors (HOTSC2), exhibiting corner Majorana states protected by C4 symmetry and reflection symmetries. By calculating the 2D Zak phase, we derive the topological phase diagram of the system and demonstrate the bulk-edge correspondence. Finally, we analyze the finite size scaling behavior of the topological properties. Our results can serve to design new 2D materials with non-zero Zak phase and robust edge states.

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Anderson disorder-induced nontrivial topological phase transitions in two-dimensional topological superconductors

Physical Review B ◽

10.1103/physrevb.103.115430 ◽

2021 ◽

Vol 103 (11) ◽

Author(s):

Hai-Bin Wu ◽

Jian-Jun Liu

Keyword(s):

Phase Transitions ◽

Topological Phase ◽

Two Dimensional ◽

Topological Superconductors ◽

Topological Phase Transitions

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Manipulation of hot carrier cooling dynamics in two-dimensional Dion–Jacobson hybrid perovskites via Rashba band splitting

Nature Communications ◽

10.1038/s41467-021-24258-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jun Yin ◽

Rounak Naphade ◽

Partha Maity ◽

Luis Gutiérrez-Arzaluz ◽

Dhaifallah Almalawi ◽

...

Keyword(s):

Transient Absorption ◽

Phonon Scattering ◽

Transient Absorption Spectroscopy ◽

Band Model ◽

Two Dimensional ◽

Spintronic Devices ◽

Hot Carrier ◽

Band Splitting ◽

Perovskite Materials ◽

Spin Polarized

AbstractHot-carrier cooling processes of perovskite materials are typically described by a single parabolic band model that includes the effects of carrier-phonon scattering, hot phonon bottleneck, and Auger heating. However, little is known (if anything) about the cooling processes in which the spin-degenerate parabolic band splits into two spin-polarized bands, i.e., the Rashba band splitting effect. Here, we investigated the hot-carrier cooling processes for two slightly different compositions of two-dimensional Dion–Jacobson hybrid perovskites, namely, (3AMP)PbI4 and (4AMP)PbI4 (3AMP = 3-(aminomethyl)piperidinium; 4AMP = 4-(aminomethyl)piperidinium), using a combination of ultrafast transient absorption spectroscopy and first-principles calculations. In (4AMP)PbI4, upon Rashba band splitting, the spin-dependent scattering of hot electrons is responsible for accelerating hot-carrier cooling at longer delays. Importantly, the hot-carrier cooling of (4AMP)PbI4 can be extended by manipulating the spin state of the hot carriers. Our findings suggest a new approach for prolonging hot-carrier cooling in hybrid perovskites, which is conducive to further improving the performance of hot-carrier-based optoelectronic and spintronic devices.

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