Light-modulated 8-Pmmn borophene-based pure crossed Andreev reflection

Light-modulated 8-Pmmn borophene-based pure crossed Andreev reflection

Abstract

We investigate the off-resonant circularly polarized light-modulated crossed Andreev reflection (CAR) in an 8-Pmmn borophene-based normal conductor/superconductor/normal conductor junction. When the signs of Fermi energies in two normal regions are opposite, the pure CAR without the local Andreev reflection and the elastic cotunneling occurs. By using the Dirac–Bogoliubov–de Gennes equation and the Blonder–Tinkham–Klapwijk formula, the pure CAR conductance and its oscillation as a function of the junction length and the Fermi energy in the superconducting regions are discussed. It is found that the value of pure CAR conductance peak value and its corresponding value of light-induced gap increase with the increase of incident energy of electron. Furthermore, the valley splitting for the transmitted hole is found due to the presence of tilted velocity of borophene. Our findings are beneficial for designing the high efficiency 8-Pmmn borophene-based nonlocal transistor and nonlocal valley splitter without local and non-entangled processes.

Summary for Non-Scientists

Researchers are studying a phenomenon called crossed Andreev reflection (CAR) in a special structure made with borophene, a two-dimensional material composed of boron atoms. This structure is a combination of normal conductors (materials that conduct electricity) and a superconductor (a material that can conduct electricity with zero resistance).


Here's a breakdown of their work:

  • They used circularly polarized light to modulate CAR in this borophene-based structure. CAR is a process where an electron from one normal conductor is reflected as a hole in another, creating a paired state in the superconductor.
  • They focused on cases where the Fermi energies (energy levels of electrons) in the two normal regions are opposite. This setup allows for pure CAR to occur without other interfering processes.
  • They used advanced mathematical equations and models to study how CAR behaves under different conditions, such as changes in the length of the junction and the Fermi energy in the superconducting regions.
  • They discovered that the CAR conductance (a measure of how well CAR occurs) increases with higher incident electron energy and that the transmitted holes show a splitting due to the tilted velocity of borophene.

Their findings suggest that this borophene-based setup can be very efficient for creating advanced devices like nonlocal transistors and valley splitters, which have applications in future electronic technologies.

Source :
New Journal of Physics
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