Chains of magnetic atoms with either strong spin-orbit coupling or spiral magnetic order which are proximity-coupled to superconducting substrates can host topologically non-trivial Majorana bound states. The experimental signature of these states consists of spectral weight at the Fermi energy which is spatially localized near the ends of the chain. However, topologically trivial Yu-Shiba-Rusinov in-gap states localized near the ends of the chain can lead to similar spectra. Here, we explore a protocol to disentangle these contributions by artificially augmenting a candidate Majorana spin chain with orbitally-compatible nonmagnetic atoms. Combining scanning tunneling spectroscopy with ab-initio and tight-binding calculations, we realize a sharp spatial transition between the proximity-coupled spiral magnetic order and the non-magnetic superconducting wire termination, with persistent zero-energy spectral weight localized at either end of the magnetic spiral. Our findings open a new path towards the control of the spatial position of in-gap end states, trivial or Majorana, via different chain terminations, and the realization of designer Majorana chain networks for demonstrating topological quantum computation.
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http://dx.doi.org/10.1038/s41467-020-18540-3 | DOI Listing |
Sci Bull (Beijing)
January 2025
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea; Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea; Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea; POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics, Pohang 37673, Republic of Korea. Electronic address:
Band topology has emerged as a novel tool for material design across various domains, including photonic and phononic systems, and metamaterials. A prominent model for band topology is the Su-Schrieffer-Heeger (SSH) chain, which reveals topological in-gap states within Bragg-type gaps (BG) formed by periodic modification. Apart from classical BGs, another mechanism for bandgap formation in metamaterials involves strong coupling between local resonances and propagating waves, resulting in a local resonance-induced bandgap (LRG).
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Universität Tübingen, Institute of Physical and Theoretical Chemistry, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
The versatile optoelectronic properties of the material class of III-V semiconductors enable the highest performance in photovoltaic and photoelectrochemical solar cells. While a high level of control and understanding with respect to different surface reconstructions of these compounds in gas-phase ambient has been reached, the situation in an electrochemical environment still poses challenges. Here, we therefore have undertaken a computational study of the InP(100) surface in the presence of hydrogen and chlorine, mimicking the contact with a hydrochloric acid-containing electrolyte, aiming at an understanding of ion adsorption and dominant surface reconstructions with respect to applied potential and electrolyte concentration.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
The pseudogap phenomena have been a long-standing mystery of the cuprate high-temperature superconductors. The pseudogap in the electron-doped cuprates has been attributed to band folding due to antiferromagnetic (AFM) long-range order or short-range correlation. We performed an angle-resolved photoemission spectroscopy study of the electron-doped cuprates PrLaCeCuO showing spin-glass, disordered AFM behaviors, and superconductivity at low temperatures and, by measurements with fine momentum cuts, found that the gap opens on the unfolded Fermi surface rather than the AFM Brillouin zone boundary.
View Article and Find Full Text PDFJ Phys Condens Matter
December 2024
Department of Physics, AKPC Mahavidyalaya, Bengai, West Bengal 712611, India.
We study the effect of periodic hopping modulation in a Su-Schrieffer-Heeger (SSH) chain with an additional onsite staggered imaginary potential (of strength). Such dissipative, non-Hermitian (NH) extension amply modifies the features of the topological trivial phase (TTP) and the topological nontrivial phase (TNP) of the SSH chain, more so with the periodic hopping distribution. Generally a weak NH potential can respect the parity-time (PT) symmetry keeping the energy eigenvalues real, while a strong potential breaksPTconservation leading to imaginary edge state and complex bulk state energies in the system.
View Article and Find Full Text PDFSmall
December 2024
School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
Introducing uniform magnetic order in two-dimensional (2D) topological insulators by constructing heterostructures of TI and magnet is a promising way to realize the high-temperature Quantum Anomalous Hall effect. However, the topological properties of 2D materials are susceptible to several factors that make them difficult to maintain, and whether topological interface states (TISs) can exist at magnetic-topological heterostructure interfaces is largely unknown. Here, it is experimentally shown that TISs in a lateral heterostructure of CrTe/Bi(110) are robust against disorder, defects, high magnetic fields (time-reversal symmetry-breaking perturbations), and elevated temperature (77 K).
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