We show that a topological phase supporting Majorana fermions can form in a two-dimensional electron gas (2DEG) adjacent to an interdigitated superconductor-ferromagnet structure. An advantage of this setup is that the 2DEG can induce the required Zeeman splitting and superconductivity from a single interface, allowing one to utilize a wide class of 2DEGs including the surface states of bulk InAs. We demonstrate that the interdigitated device supports a robust topological phase when the finger spacing λ is smaller than half of the Fermi wavelength λ(F). In this regime, the electrons effectively see a "smeared" Zeeman splitting and pairing field despite the interdigitation. The topological phase survives even in the opposite limit λ > λ(F)/2, although with a reduced bulk gap. We describe how to electrically generate a vortex in this setup to trap a Majorana mode, and predict an anomalous Fraunhofer pattern that provides a sharp signature of chiral Majorana edge states.
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http://dx.doi.org/10.1103/PhysRevLett.109.126403 | DOI Listing |
Entropy (Basel)
January 2025
School of Integrated Circuits, Tsinghua University, Beijing 100084, China.
A notable feature of systems with non-Hermitian skin effects is the sensitivity to boundary conditions. In this work, we introduce one type of boundary condition provided by a coupling impurity. We consider a system where a two-level system as an impurity couples to a nonreciprocal Su-Schrieffer-Heeger chain under periodic boundary conditions at two points with asymmetric couplings.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
National Institute for Fusion Science, Oroshi, Toki 509-5292, Gifu, Japan.
A topological constraint, characterized by the Casimir invariant, imparts non-trivial structures in a complex system. We construct a kinetic theory in a constrained phase space (infinite-dimensional function space of macroscopic fields), and characterize a self-organized structure as a thermal equilibrium on a leaf of foliated phase space. By introducing a model of a grand canonical ensemble, the Casimir invariant is interpreted as the number of topological particles.
View Article and Find Full Text PDFSoft Matter
January 2025
Department of Physics, Government College of Engineering and Textile Technology, 12 William Carey Road, Serampore, Hooghly-712201, India.
The theoretical study of instabilities, thermal fluctuations, and topological defects in the crystal-rotator-I-rotator-II (X-R-R) phase transitions of -alkanes has been conducted. First, we examine the nature of the R-R phase transition in nanoconfined alkanes. We propose that under confined conditions, the presence of quenched random orientational disorder makes the R phase unstable.
View Article and Find Full Text PDFMater Horiz
January 2025
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
The quantum anomalous Hall effect (QAHE) with a high Chern number hosts multiple dissipationless chiral edge channels, which is of fundamental interest and promising for applications in spintronics. However, QAHE is currently limited in two-dimensional (2D) ferromagnets with Chern number . Using a tight-binding model, we put forward that Floquet engineering offers a strategy to achieve QAHE in 2D nonmagnets, and, in contrast to generally reported QAHE in 2D ferromagnets, a high-Chern-number is obtained accompanied by the emergence of two chiral edge states.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
Chiral magnetic textures give rise to unconventional magnetotransport phenomena such as the topological Hall effect and nonreciprocal electronic transport. While the correspondence between topology or symmetry of chiral magnetic structures and such transport phenomena has been well established, a microscopic understanding based on the spin-dependent band structure in momentum space remains elusive. Here, we demonstrate how a chiral magnetic superstructure introduces an asymmetry in the electronic band structure and triggers a nonreciprocal electronic transport in a centrosymmetric helimagnet α-EuP.
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