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arXiv:2512.03863

Laser-induced modulation of conductance in graphene with magnetic barriers

Rachid El Aitouni, Miloud Mekkaoui, Pablo Díaz, David Laroze, Ahmed Jellal

cond-mat.mes-hallquant-phSubmitted Dec 3, 2025• Announced Dec 4, 2025
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Abstract

We study how electrons move across a graphene sheet when it encounters two magnetic barriers with a region in between that is continuously driven by laser light. Rather than acting as a static obstacle, this illuminated middle section becomes a Floquet cavity that opens new transport channels through controlled photon absorption and emission. By combining Floquet theory with the transfer matrix method, we track electron transmission through both the main energy band and the emerging photon-assisted sidebands. We find that the laser does more than modify the potential--it reshapes how electrons interact between the magnetic barriers, enabling a switch from ordinary transmission to transport dominated by photon exchange. Because the magnetic field and the optical drive are applied to separate sections of the device, the system supports interference between cyclotron-filtered motion and discrete photon-pumping channels, producing Fano resonances and angle-dependent transmission zeros that cannot appear in double magnetic or double laser barrier systems alone. Under well-defined conditions, the distance between the magnetic barriers controls the coupling between Floquet channels, allowing highly tunable resonances and even perfect transmission, despite strong magnetic confinement. We also observe that low-energy carriers are efficiently blocked by the magnetic regions, while conductance steadily rises with energy until it reaches a clear saturation plateau. This hybrid design provides a versatile way to steer graphene electrons by balancing optical pumping and magnetic momentum filtering.

Comments
13 pages, 8 figures. Version to appear in Applied Physics A

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Laser-assisted tunneling in a static tungsten diselenide WSe2_22​ barrier
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This work investigates the Floquet dynamics of electrons and excitons (particle-hole pairs) in a Dirac material referred to as Kekulé-distorted graphene. Specifically, we examine the role played by a high frequency driving electromagnetic field on the tunneling and blocking by a potential barrier on both the charged single particles as well as the neutral composite particles. We demonstrate that the small effective masses of the electron and hole for the energy spectrum of this Kekulé distorted graphene leads to practically almost perfect transmission across a symmetric potential barrier for any angle of incidence of impinging excitons. However, this unexpected Klein paradox for excitons does not hold for the single-particle electrons. The reduced total transmission of electron due to Kekulé distortion is more suppressed due to irradiation. Additionally, we calculate and investigate the exciton binding energy since the quantum tunneling of a bound electron-hole pair across a potential barrier is governed by its mass measured in the center of mass and binding energy of the composite pair. Thus, irradiation with circularly polarized light fundamentally modifies exciton formation, coherence and transport properties, thereby producing unusual topological behaviors. These behaviors are unlike conventional Dirac materials. Possible technical applications of the results arising from our investigation include valleytronics due to the folding of the valleys, thereby making intervalley coupling feasible. Other practical applications include optoelectronics due to Floquet tuning of energy spectrum and transport properties.
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We present a theoretical study of electron tunneling through a magnetic barrier in 8-Pmmn borophene, created by depositing two ferromagnetic strips on the borophene sheet. Using a low-energy effective Hamiltonian that captures the anisotropic Dirac spectrum, we solve the Dirac equation in three regions and impose wave-function continuity at the interfaces. From the resulting spinor solutions, we compute current densities and determine transmission and reflection probabilities as functions of incident energy, angle, and barrier parameters. The transmission exhibits strong anisotropy due to the tilted Dirac cones, with pronounced suppression for specific incident directions, suggesting directional filtering of carriers. We further calculate the conductance using the Landauer-Büttiker formalism, revealing that both magnetic strength and barrier width can tune the charge transport properties. The results demonstrate that engineered magnetic barriers in 8-Pmmn borophene enable precise control over electron flow, offering a platform for anisotropic transport control and tunable quantum devices. The interplay between the intrinsic anisotropy of borophene and external magnetic barriers provides rich opportunities to manipulate Dirac fermions in two-dimensional systems.